Aside from the terrible precedent it sets, it's the "per month" thing that's really troubling. People are really okay with spending what could eventually be hundreds of dollars on some additional storage space an auction house slots? It's absurd. If they're going to go down that route (and they really, really shouldn't have), they should at least do the sane thing and make it a one time fee. Even free-to-play MMOs get that part right.