This is a terrible idea and I wont support it one bit.Don't take it personally, a lot of people have brought up this terrible idea. I think that playing as a variety of races could work in a game like tactics but you can make your whole squad. The main series is for the PC to be human, and human alone.
Well I don't buy that I mean come on....ghouls are people too ya know....
But yeah I wouldn't mind if you could choose at the beginning ghoul/super mutant/human but its not something that I require even in future games. I will still enjoy them playing as my human character. It would be nice for variety and add even more playability. Instead of 3-4 time playing through (good/bad/neutral) you get 6-8 more times if you want it.
Anyway I don't see it happening anytime soon, maybe when the next generation consoles come out and systems/engines are able to handle a lot more data but until then this probably wont happen.
Off topic P.S. Is the guys that made the gamebryo engine making Bethesda a new engine to play with? or are they going a different route altogether? IDtech?