A Place by Any Other Name

Can somebody please explain to me why the Indians have changed the names of three of their best known cities?

I refer, of course, to: Bombay, Calcutta and Madras. (I'm sure these places are not alone, and there is a rolling program of doing this.) There is a governmental foolishness about this kind of thing that defies description let alone understanding. It's like London being renamed by some crazy despot "Londinium", or the American government foisting "New Amsterdam" on New York.

What purpose does it serve and who is the maniac behind it? Perhaps his brother is a publisher of atlases and globes.