It is said that because Krsna was constantly performing various types of sacrifices and was inviting the demigods from the higher planetary systems,the demigods were almost always absent from their consorts.Therefore the wives of the demigods, regretting the absence of their husbands, began to pray for the appearance of Lord Buddha, Krsna's ninth incarnation, who appears in the age of Kali. In other words, instead of being pleased that Lord Krsna had come, they began to pray for Lord Buddha, who is the ninth incarnation, because Lord Buddha stopped the ritualistic ceremonies and sacrifices recommended in the Vedas in order to discourage animal-killing.The demigods' wives thought that if Lord Buddha appeared, all kinds of sacrifices would be stopped, and thus their husbands would not be invited to such ceremonies and would not be separated from them.Sometimes it is inquired, "Why don't the demigods from higher planetary systems come to this earth planet nowadays?" The plain answer is that since Lord Buddha appeared and began to deprecate the performance of sacrifice in order to stop animal-killing on this planet, the process of offering sacrifices has been stopped, and the demigods do not care to come here anymore.
(from Nectar of Devotion)
