In my opinion, the genre is pretty well defined. Baldur's Gate is an RPG, as is Xenoblade, The Last Story, the Tales Series, Skyrim, Final Fantasy, Dragon Quest, etc. Mass Effect isn't an RPG, but has some elements that are RPG light. That doesn't make it a full fledged RPG, though. I play Mass Effect the same way I play Gears of War and you can go through the whole game with the game simply handling your "levels" and never notice the RPG parts at all. I tried this, in fact, by not even bothering with putting points into anything. I'm good with the gun and a couple of abilities and that's good enough to win. Even the "quests" are nothing and don't really gain you anything. Mass Effect 3 is a straight up shooter.
Don't get me wrong, there's nothing wrong with this. I had a lot of fun with it, but it's not an RPG.