I don't see why not. It's not like it changes the gameplay any more than being able to turn on 25% gravity and 300% speed, or even no shields.
Of course it's a little different than what's been an option in previous games but they've already said you'd have more customization options than every before. Given how controversial it is I'd figure they'd at least give players that option to see if they really do enjoy the game more that way. The only reason I could think they wouldn't include it is out of pure stubbornness.
I think the wizards at Bungie would be able to go a lot further than that and really create their own gametypes to a whole new level. They've done great with giving options to adjust player traits so why not weapon traits. I'd love to go into Forge or under an advanced option in custom gametypes and change attributes of weapons: clip size, damage, bloom, etc. They could also do something similar with adjustable AAs. Seems like the natural evolution of custom game options, from player traits, expanded objective customization, to weapons, and AAs.