Hey, I actually like the piece a lot for those very reasons. As others have stated, the painting shows characters engaged in very much Neutral (or possibly Evil, depending on what kind of dragon that is) behavior. This isn't the after-math drawing you find so much these days, where the bloodied, exhausted hero leans against a tree near the body of a gargantuan foe. These adventurers all look pretty uninjured, posing next to a creature about the same size as them, in a way that suggests, "We killed this thing for sport and glory." Comparisons to fishing photos are apropos, and I imagine Elmore had that at least in part of his mind when he painted it. On the other hand, dragons are far more intelligent and sentient than trout.
Personally, I want my campaigns to allow for player characters to fill the dirtbag adventurer role as easily as the hero adventurer role. The one thing I don't want in my campaign is for players to play dirtbag adventurers, but feel as if they're playing total heroes. The LG heroic murder hobo is a delusional psychopath, and, if I'm doing my job, the campaign world relates to him or her as such. (Within the bounds of ultimately having fun, of course. I don't want to keep some sort of moral and ethical score and use my DM screen as a pulpit to impose a draconian morality on my players, at least not beyond some ground rules that are accepted up-front.)
It's hardly an either/or conundrum. Characters can be generally moral and still want to go skin some displaced beast pups because they fetch the best price. And the whole murder hobo bit is overwrought: in a world in which the penalty for banditry is a beheading after a "he said" trial, the paladin is breaking any code by wiping out the brigand camp to a man. But this is sort of a tangential discussion to the awesomeness of 5E art.
