Subscriptions are still where the real money is made for MMOs.
True, but right now one of the main problems a new MMO faces is gaining traction and continuing to grow even after 2,3 months from launch. F2P really helps with this, as it makes it more easy for new players to try it out and also play casually anytime they feel like it. And in the end this might also mean more revenue.
This being said, I completely agree with everything else you say when it comes to sub vs f2p. Monthly sub makes perfect sense for MMOs. It supports the constant development of the game and it has a minimal effect on the actual game-play.
I also think that what Blizzard is doing with WoW right now is pretty much the perfect revenue model, with just one small change. Keep the sub, but make it cheaper, like maybe 9.5$ To boost the revenue, use paid services (like race / look / faction etc) + pure vanity rare-ish sales (in the sense that dont move too many appearence items in the $ shop). It's way more than enough to support development and make a nice buck and it's also fair to the players.