It just seems to me that it loses a bit of it's functionality when you can repair to 100 from the outset... I mean armor I can see because it's piecemail work but guns and the like are pretty complicated things. I'm more curious if it was meant to be able to 100% from the outset or if that was a mistake.
Well, you say that now, but try repairing something valuable or rare with a low repair skill. Sure, no big deal to repair a 9mm pistol to 100% by using 3 or 4 other pistols, because they're cheap and plentiful... but you don't want to waste 4 sniper rifles (or w/e) to get one fully functional one.
As to repairing guns being too complicated - not really - you "lose" the item you're repairing with, so it's like you're just replacing worn parts.