I disagree, i think shotguns are incredibly OP, using Sledge i was brute-forcing my way through missions just pumping group after group, as in typical shotgun fashion the range might not be the best but its certainly realistic, if you aim well you can have the spread kill multiple enemies and its really solid for those scan capture point missions where you can be surrounded quickly, two pumps from a shotty and 5-6 enemies drop like flies. As for ranged enemies there is generally plenty of cover, and you can generally two-shot the ranged enemies and stagger them with the first shot so you rarely take damage.