Thrall, Malfurion, Illidan, Jaina, Garrosh, Khadgar and every single hero you are not in control of for being powerful? You do just as ridiculous feats and pull off the impossible against things that should many times over have killed you.
To be so bugged by the so called Mary Sue characters in the lore I think is downright hypocritical, and if being powerful is so offensive and bad writing to you, than you're being more double minded playing this game which from start to finish portrays you as a ridiculously overpowered hero.
My recommendation, quit !! If not, put up, you either like this sort of thing or you don't, but no more hating just because they're powerful, because you are also insanely so, if they are written badly as characters, that's a different story - but don't keep criticising without offering a better solution - otherwise you can't make that assertion, it's one thing to say you don't like it, it's another thing to come out and say, it's badly written.