“The Ethiops say that their gods are flat-nosed and black, While the Thracians say that theirs have blue eyes and red hair. Yet if cattle or horses or lions had hands and could draw, And could sculpt like men, then the horses would draw their gods Like horses, and cattle like cattle; and each they would shape Bodies of gods in the likeness, each kind, of their own.”
The gods of India were mainly imposed by the Aryan invaders of 2000-1200 BCE. Those were light-skinned people who spoke an Indo-European language, which is why Hindi is related to most of the languages of Europe. Anyway, the light-skinned Aryans dominated Indian society--to the extent of giving the country its name--and so their conceptions of the gods' complexion became dominant along with the caste system and other social institutions.
If Indians are trying to recast their gods with darker skin, they must be trying to re-caste their society in more egalitarian terms as well. We'll see whether the lower castes and the southern, relatively Dravidian, peoples prevail.