1. Most PvE engagements I find myself in are at a range shotguns aren't effective. 2. A burst from a fusion rifle can output more consistent damage at better ranges, while still being nearly as good up close 3. When it comes to bosses, Fusion's are good because they can usually get all the bursts on the target, and snipers can hit crit points for great damage at range. Shotguns, on the other hand, put you into the range of every bosses insta-death AoE melee attack. Unless they buff the range and tighten shotguns cone of fire, they're never going to be useful outside of trash-clearing and PvP.