Honestly it just requires a bit more finesse to use a fusion rifle only because of the daily. No skill required to pull a trigger while holding a shotgun (I know I've just scared myself turning a corner and pulled the trigger Cuz of a knee jerk reaction and suddenly I've got a kill) but with fusion rifles you have to lead into the shot and take time to plan out your move. Plus I see havoc pigeon (sidearm) a few times rather then just once or twice. Shotguns, auto rifles, snipers, and scout rifles take less time to figure out so are used more often by those of less skill.