I personally don't care one way or the other for guns, but can definitely see the arguments against them.
Crossbows, slings, javelins, etc. however would be a welcome addition (or re-introduction for some of them). And on the one-handed crossbow thing, there have been crossbows made that could easily be fired one handed, but would need to be pre-loaded if you want use two as you would obviously need 2 hands to load.
That actually made me think of the main character of the books in the Dragonlance series Rise of Solamnia, There were a few times when fighting out numbered he would take 2 crossbows from under his cloak, fire them and then draw his sword.