Yeah, the hero is just going to have to be violent, but he doesn't have to like it, he can look for other ways of achieving his goals.
As you said, there are other legitimate ways of creating good gameplay(and I hate it when people make protagonists that are morally questionable/bad). However, in video games, fighting is usually a major part of the game. I've rarely played a game I liked that didn't have at least some
combat in it.
And the fighting itself doesn't have to be too violent, what do blood and gore actually add to the game?
And about enemies ganging up on you, I think it would be better if more games had a few challenging enemies, not just loads of weak ones like in mario(At least in RPGs, mario can get away with it because it's a different type of game). Imagine if the common enemy was a little closer to a boss fight, instead of 20 goblins, maybe 2 skilled wizards.