Target assist is pretty much aim assist. It helps you to track your targets. Take it off and then play. But back on topic. I don't like noob tubes, it's an easy way to get cheap kills on a player. But black ops had the right way of dealing with it, no resupplies, i'd rather see it limited to one shot, and only half damage if it hits you point blank instead of an instant kill ( i know it's not that realistic). It still won't stop me from picking them up if i kill you and firing it back at you
I've said it before and I'll say it again, if the weapons are balanced (and that means effective use, situations, speed, power, skill required and quantity) then there is no problem for launchers.
Realism of weapon use in combat is hard to portray in a game, but Treyarch are good at portraying the effectiveness instead. At the expense of having fully damaging endless nooby grenade explosions, or a weapon that doesn't fit, they can tweak it. Black Ops was ok.