You'll probably still want a full set of exotic weapons and gear so you can rotate them around as needed. For instance if you want to use an exotic sniper rifle all the time, you'll probably need 3 snipers, one of each ammo type, and then if you lock your weapon for the damage bonus, you may want to get another one again so that you can have a version with a different scope or a different set of talents. Sage showed that exotics can unlock additional parts of your talent tree too for free, so having tons of exotics equipped would probably be rather overpowered.