Well, on PC's you can make them tall or short, but yeah, it'd be nice if there were more body types in terms of weight. Not just in NV either. Not something most games do too much of tho.
This.
In Oblivion I made Madoc the mrazy Mgnoe.
Using a Xviali mod and shrinking it down to minimum, then just added blue pants, an ugly but cheeky face.. and a lovely attitude to murder.
However with the damn metheod of making more stable but not very flexible to mod meshes that are the trend, the adding of custom sizes will be difficult.