You had a problem with it on account of possible effects of recoil, in other words the feasibility of it firing that fast. The videos handily proved that recoil with a grenade launcher, even one firing at six rounds every three seconds, wouldn't be a problem for an unarmored man, never mind one who would weigh as much as a small vehicle. The fact that you can see it recoil is irrelevant, if it wasn't able to handle it in the first place it'd just tip over instead of, you know, continuing to fire. You also made the idiotic complaint of "zomg C&C!" as if that means something. Oh noes, C&C had tanks! Quick, we must remove the Siege Tank!
As far as Marauders using stimpacks, I couldn't care less. If removing stims from them helps the game, that's fine by me.