Well spotted Crovax!
Just bring back the double shotgun from tfc, rightclick for double shots
Or some variety to the shotguns - (firepower, spread, rate and clip size). Real worldshotguns have a whole range of ammo available - from single slugs (for stopping trucks and killing hephalumps) to duckshot and dustshot (easy hit, little/no dmg, blinds target for 1 s on headshot - sort of a cover-me-I'm-runnning weapon?). Add in the beanbag rounds, door jam rounds and incendiary shot and there should have been more variety from the off.
I kinda liked the idea of a 1 shot engie weapon. Very powerful at close range but massive spread and impossible to aim except withing almost melee range. No reloading (or a very, very long reload time). Defensive only in effect, or a near-suicidal close range weapon (we're talking on a par with a wide angle, short range taunt kill here with no reload).