to me an MMO having a subscription makes sense, they have overhead, so the players should be covering that. That's the way a business runs.
BUT, that also means they have to meet the expectations of the price point their asking, it's not free so they can't just say that you get what you get.
If they can pull it off being worth $15/month (which it currently isn't, imo), then I have no problem with it. That's going to be tough though, most people won't play EVE Online due to $20/month subscription, and that game is near perfect for what it was going for.