Do you honestly think dps is the only reason we bring various ammos? I've used lesmok and charged rounds in the merc, to great effect. There's only 4 guns the require no skill in the game, the gat, and the carronades, and the flamer. As for the heavy flak, lesmok and loch are both used. There isn't a point in buffing a loch shot from a heavy flak, because that will kill any ship stripped from armor except the galleon. And i dont believe that buffing it will one shot a galleon. As for the artemis, i've used lesmok and busrt rounds, with lesmok a artemis can compete with merc range, assuming the merc isn't using lesmok. The flamer can use greased, lesmok, and burst effectively at various ranges. And no matter what you say, there will always be people who prefer to be a gunner then a engie. It won't matter how sound your logic is, people do not run on logic alone.
I will agree that the gunner should possibly get another tool slot, give a gunner a pipe wrench and a buff hammer, then they can start pumping out some serious damage. But I do not believe muse will do this, as it would break the balance.