Here's where we keep our suggestions:
http://www.gamesas.com/index.php?/topic/1178163-fallout-4-speculations-suggestions-and-ideas/
The problem with different races is that you're going to have to start locking off large parts of the game depending on which race the player selects. Thats more content an individual player may not end up seeing, and more work requied to get the same sort of "Game length" for everyone.
But playing as a supermutant was actually one of the intentions in FO1's design....