Seems like almost every MMO has to go F2P today... I think we're just MMOed out, in many ways. When it was new and exciting, it was easier to justify dropping $15 a month to play, now it's become harder to warrant spending all that money, even if you do generally get far more gaming hours than a typical game release.
Guild Wars, in my estimation, did it right... And rocked the boat on the status quo at the time. Pay more up front for the game (like you would any single player or co-op game), and that's what you get, with minor patches of course. New expansion comes out, you buy that up front if you want it, if not just keep playing what you have. That sales model created an interesting economic model - rather than charging a subscription and rolling out marginal "free" expansions, with the occasional stellar expansion, you have to roll out full-on expansive and quality expansions that make consumers want to pay for the product. It put quality first, because a crap expansion will never sell enough to recoup the development costs. Then adding the micro-transactions for just cosmetic stuff and convenience bonuses made it easy to maintain the game's upkeep.