I think his point was more, it's a little weird to add an alternative fire option to just one gun, out of all the guns we have. If you were going to give the Heavy Carronade an alt-fire, it makes sense that you'd need to give most (or at least some) other guns an alt-fire as well. I tend to agree, though I'm not necessarily opposed if that's the way we'd want to take it.
exactly, if you add an alternate firing/special ability (what ever you want to call them) option you have to add them to the vast majority of them, then you have to have some sort reason why this isnt the way the gun functions normally, which is essentially a cooldown (it might not be a timer but anything that stops you from using somthing for a short time is a cooldown). once you apply these abilities to the other guns, it snowballs and you have all sorts of balance issues.
the reason i say it puts it into a more arcade/cartoonish place is because it suspends the way the gun itself functions normally to pull off some sort of powerful move, which pushes the game farther towards complete suspension of realism (as opposed to the quasi-realistic feel the game has currently, where things are kinda realistic but balance and aesthetic takes priority).
furthermore a secondary fire option isnt really necessary with the ammo system. you can change the way the gun functions by changing your ammo types. the ammo is basically the special abilities available to each gun. if you try to pair the two systems you create a monster interms of balance, shooting two barrels at once for instance, ( although technically i believe the carronade already does this normally it just loads two rounds of double barreled fire in its mechanism but still for the sake of argument) conveys increased damange, you would have to balance that with the ammo that already does more damage. and then for every gun in the game with a secondary ability, you would basically be making a new game interms of functionality and balance.
