Kuvera is one of the demigods, so one may put forward the argument, "Why did Dhruva Mahārāja take a benediction from a demigod?" The answer is that for a Vaiṣṇava there is no objection to taking a benediction from a demigod if it is favorable for advancing Kṛṣṇa consciousness. The gopīs, for example, worshiped Kātyāyanī, a demigoddess, but the only benediction they wanted from the goddess was to have Kṛṣṇa as their husband.
(Srimad Bhagavatam------4:12:9------purport).

It is said, vaiṣṇavānāṁ yathā śambhuḥ: Lord Śiva is the best of all devotees. Therefore all devotees of Lord Kṛṣṇa are also devotees of Lord Śiva. In Vṛndāvana there is Lord Śiva's temple called Gopīśvara. The gopīs used to worship not only Lord Śiva but Kātyāyanī, or Durgā, as well, but their aim was to attain the favor of Lord Kṛṣṇa.
(Srimad Bhagavatam------4:24:30------purport).

Śukadeva Gosvāmī said: During the first month of the winter season, the young unmarried girls of Gokula observed the vow of worshiping goddess Kātyāyanī. For the entire month they ate only unspiced khichrī.
(Srimad Bhagavatam------10:22:1-------translation).

Each of the young unmarried girls performed her worship while chanting the following mantra. "O goddess Kātyāyanī, O great potency of the Lord, O possessor of great mystic power and mighty controller of all, please make the son of Nanda Mahārāja my husband. I offer my obeisances unto you."
(Srimad Bhagavatam------10:22:4-------translation).

Thus for an entire month the girls carried out their vow and properly worshiped the goddess Bhadrakālī, fully absorbing their minds in Kṛṣṇa and meditating upon the following thought: "May the son of King Nanda become my husband."
(Srimad Bhagavatam------10:22:5-------translation).

Go now, girls, and return to Vraja. Your desire is fulfilled, for in My company you will enjoy the coming nights. After all, this was the purpose of your vow to worship goddess Kātyāyanī, O pure-hearted ones.
(Srimad Bhagavatam------10:22:27-------translation).

According to Vedic civilization, unmarried girls from ten to fourteen years of age are supposed to worship either Lord Śiva or goddess Durgā in order to get a nice husband. But the unmarried girls of Vṛndāvana were already attracted by the beauty of Kṛṣṇa. They were, however, engaged in the worship of goddess Durgā in the beginning of the Hemanta season (just prior to the winter season). The first month of Hemanta is Agrahāyana (October–November), and at that time all the unmarried gopīs of Vṛndāvana began to worship goddess Durgā with a vow. They first ate haviṣyānna, a kind of food prepared by boiling together mung dhal and rice without any spices or turmeric. According to Vedic injunction, this kind of food is recommended to purify the body before one enacts a ritualistic ceremony. All the unmarried gopīs in Vṛndāvana used to daily worship goddess Kātyāyanī early in the morning after taking a bath in the river Yamunā. Kātyāyanī is another name for goddess Durgā. The goddess is worshiped by preparing a doll made of sand from the bank of the Yamunā. It is recommended in the Vedic scriptures that a deity may be made from different kinds of material elements: it can be painted, made of metal, made of jewels, made of wood, earth or stone or can be conceived within the heart of the worshiper.
(Krsna Book).

The unmarried gopīs used to prepare the deity of goddess Durgā and worship it with candana pulp, garlands, incense, lamps and all kinds of presentations—fruits, grain and twigs of plants. After worshiping, it is the custom to pray for some benediction. The unmarried girls used to pray with great devotion to goddess Kātyāyanī, addressing her as follows: "O supreme external energy of the Personality of Godhead, O supreme mystic power, O supreme controller of this material world, O goddess, please be kind to us and arrange for our marriage with the son of Nanda Mahārāja, Kṛṣṇa." The Vaiṣṇavas generally do not worship any demigods. Śrīla Narottama dāsa Ṭhākura has strictly forbidden all worship of the demigods for anyone who wants to advance in pure devotional service. Yet the gopīs, who are beyond compare in their affection for Kṛṣṇa, were seen to worship Durgā. The worshipers of demigods sometimes mention that the gopīs worshiped goddess Durgā, but we must understand the purpose of the gopīs. Generally, people worship goddess Durgā for some material benediction. Here, the gopīs prayed to the goddess to become wives of Lord Kṛṣṇa. The purport is that if Kṛṣṇa is the center of activity, a devotee can adopt any means to achieve that goal. The gopīs could adopt any means to satisfy or serve Kṛṣṇa. That was the superexcellent characteristic of the gopīs. They worshiped goddess Durgā completely for one month in order to have Kṛṣṇa as their husband. Every day they prayed for Kṛṣṇa, the son of Nanda Mahārāja, to become their husband.
(Krsna Book).

Appearing on the scene, Kṛṣṇa immediately collected all the garments of the gopīs, climbed up into a nearby tree, and with a smiling face began to speak to them.
"My dear girls," He said, “please come here one after another and pray for your garments and then take them away. I’m not joking with you. I’m just telling the truth. I have no desire to play any joke with you, for you are tired from observing the regulative principles for one month by worshiping goddess Kātyāyanī. Please do not come here all at once. Come alone; I want to see each of you in your complete beauty, for you all have thin waists. I have requested you to come alone. Now please comply.”
(Krsna Book).

When the gopīs saw that Kṛṣṇa was strong and determined, they had no alternative but to abide by His order. One after another they came out of the water, but because they were completely naked, they tried to cover their nakedness by placing their left hand over their pubic area. In that posture they were all shivering. Their simple presentation was so pure that Lord Kṛṣṇa immediately became pleased with them. All the unmarried gopīs who prayed to Kātyāyanī to have Kṛṣṇa as their husband were thus satisfied. A woman cannot be naked before any male except her husband. The unmarried gopīs desired Kṛṣṇa as their husband, and He fulfilled their desire in this way.
(Krsna Book).

Although Kṛṣṇa cheated the young unmarried gopīs and made them stand naked before Him and enjoyed joking words with them, and although He treated them just like dolls and stole their garments, they were still pleased with Him and never lodged complaints against Him. This attitude of the gopīs is described by Lord Caitanya Mahāprabhu when He prays, "My dear Lord Kṛṣṇa, You may embrace Me or trample Me under Your feet, or You may make Me brokenhearted by never being present before Me. Whatever You like, You can do, because You have complete freedom to act. But in spite of all Your dealings, You are My Lord eternally, and I have no other worshipable object." This is the attitude of the gopīs toward Kṛṣṇa.
Lord Kṛṣṇa was pleased with them, and since they all desired to have Him as their husband, He told them, "My dear well-behaved girls, I know of your desire for Me and why you worshiped goddess Kātyāyanī, and I completely approve of your action. Anyone whose full consciousness is always absorbed in Me, even if in lust, is elevated. As a fried seed cannot fructify, so any desire in connection with My loving service cannot produce any fruitive result, as in ordinary karma."
(Krsna Book).

The gopīs' attitude toward Kṛṣṇa, although seemingly lusty, should not be considered to be like the lusty desires of ordinary women. The reason is explained by Kṛṣṇa Himself. Activities in devotional service to Kṛṣṇa are transcendental to any fruitive result.
"My dear gopīs," Kṛṣṇa continued, "your desire to have Me as your husband will be fulfilled because it is with this desire that you worshiped goddess Kātyāyanī. I promise you that during the next autumn season you shall be able to meet with Me, and you shall enjoy Me as your husband."
(Krsna Book).

From the Vedic literature it appears that when a theatrical actor dances among many dancing girls, the group dance is called a rāsa dance. When Kṛṣṇa saw the full-moon night of the śarat season, decorated with various seasonal flowers—especially the mallikā flowers, which are very fragrant—He remembered the gopīs' prayers to goddess Kātyāyanī, wherein they prayed for Kṛṣṇa to be their husband. He thought that the full-moon night of the śarat season was just suitable for a nice dance. So their desire to have Kṛṣṇa as their husband would then be fulfilled.
(Krsna Book).

While Kṛṣṇa was enjoying the company of the gopīs in the rāsa dance, the astonished demigods and their wives gathered in the sky. The moon, being afflicted with a sort of lust, began to watch the dance and became stunned with wonder. The gopīs had prayed to the goddess Kātyāyanī to have Kṛṣṇa as their husband. Now Kṛṣṇa was fulfilling their desire by expanding Himself in as many forms as there were gopīs and enjoying them exactly like a husband.
(Krsna Book).

Most of the gopīs in their previous lives were great sages, expert in the study of the Vedas, and when Lord Kṛṣṇa appeared as Lord Rāmacandra they wanted to enjoy with Him. Lord Rāmacandra gave them the benediction that their desires would be fulfilled when He would appear as Kṛṣṇa. Therefore the desire of the gopīs to enjoy the appearance of Lord Kṛṣṇa was long cherished. So they approached goddess Kātyāyanī to have Kṛṣṇa as their husband.
(Krsna Book).

The cowherd men, who had come to execute the ritualistic function of worshiping Lord Śiva and Ambikā, finished their business and prepared to return to Vṛndāvana. While returning, they recalled the wonderful activities of Kṛṣṇa. By relating the incident of Vidyādhara's deliverance, they became more attached to Kṛṣṇa. They had come to worship Lord Śiva and Ambikā, but the result was that they became more and more attached to Kṛṣṇa. Similarly, the gopīs worshiped goddess Kātyāyanī to become more and more attached to Kṛṣṇa. It is stated in the Bhagavad-gītā that persons who are attached to worshiping demigods like Lord Brahmā, Śiva, Indra and Candra for some personal benefit are less intelligent and have forgotten the real purpose of life. But the cowherd men, inhabitants of Vṛndāvana, were no ordinary men. Whatever they did, they did for Kṛṣṇa.
(Krsna Book).

The gopīs worshiped goddess Kātyāyanī to get Kṛṣṇa as their husband; similarly Rukmiṇī was thinking of the various types of demigods not for material benefit but in respect to Kṛṣṇa. Praying to the demigods to achieve the favor of Kṛṣṇa is not irregular, and Rukmiṇī was fully absorbed in thoughts of Kṛṣṇa.
(Krsna Book).