This is an interesting point, I think, and a good argument for more generic weapons.Actually, no, a tighter range of weapon damages wouldn't be good. Look at Fallout 2, even with that broad range of weapon damage, how many weapons were there that were redundant?
After all, in "real life" you can shoot someone with your 9mm sig or .45 1911 and they will most likely be in a somewhat comparable state afterwards. Especially when you apply the digitisation and loss of resolution which is inherent when trying to convey the fine points of the different pistols and ammunitions in a game.
Of course in reality, two very similar guns (in terms of things like stopping power or effective range/accuracy) could perform in a very different manner depending on user preference and experience.
But this is far to subtle to model well in a game, IMO.
I think that the way to go is to make things like ROF and range more dependant on the users skill, and less on the weapon.