Especially in PvE, being able to get head shots the majority of the time with just about any primary weapon both puts a damper on playing for a challenge and makes using secondary or heavy weapons obsolete, shotguns are pretty much useless because a head shot with a hand cannon or scout rifle out damages it, the charge time for fusions rifles give your primary a better dps because of the sim assist, and you usually end up just saving sniper ammo on the tough enemies that are supposed to be a challenge but you can kill way too easily with the aim assist on the snipers. Obviously there are also AA problems in PvP too but I prefer close range when it comes to PvP, so I never really used the sights much.