Since the premise of this game is really about the balance of DPS and survival, most people are not jumping in killing everything with shotgun since shotgun does not provide the most DPS. Since we have really OP weapons like ice breaker, it becomes an unconscious decision of the best mix of DPS and survival hence why ice breaker is so coveted. We then have Ghorn where you could go in and just shoot rockets from far or close and kill everything. Given better substitutes and the innate desire to utilize the most efficient method in beating a boss/strike/mission, we'd all tend towards the strong weapons. If you want to have fun or mess around or find niche uses for shotguns in PVE raids etc. then by all means.