It might seem a bit harsh, but lets face it, it really should be allowed to fire on downed enemies. It would make saving those who are downed that much more special, and stop some guy essentially just spawning a trail of vengeful dead behind you if you advance down the trench
Also, it would be nice to move, if not just turn, the damn AT guns.
Its incredibly annoying and floaty to try to tow your AT guns to the front line and then make a whole turn with the entire truck to turn that bad boy around. If I can pull out a headhog tank trap out of my ''pocket'' and slap down infinite concrete dragon teeth in the pacific I think i have the strength to turn an AT canon MADE to be handled by non mechanised troops!