I think legendary guns should be able to be customized with a selection of attributes which already exist in the game. There should be a dealer in the tower to sell these mods. The new mod would take the place of an attribute which is already on the gun. For example, I have (and love) Another NITC equipped for my warlock. It has explosive rounds as an attribute. A friend of mine had the same gun but without the explosive rounds. He would like to have my version of the gun. Why shouldn't he be able to do that? I don't see why we shouldn't be able to add weapon mods to the guns we love which could accommodate individual play styles...
** I realize there will be posts telling me how much the NITC sucks. Please avoid the urge to do this do we can all avoid the "better gun" debates that frequent sidetrack these forums. Thanks
EDIT: A weapon mod I would like to see is the ability to turn bullet weapons into energy or laser weapons. No effect to damage just the visual. Any specific mods you would like to see?