Just in answer to a few other points: voice comms with a MMORPG is easy via a secondary channel like Skype or Messenger, I do it all the time; you *do* get to 'pick your friends' on-line in the same way you do around a table, you can ignore people you don't like, as well as build guilds with people you do; you *do* have to work with other people's schedules on-line when you're trying to organise high level raids and other joint ventures. Thusly the lines aren't quite as distinct as perhaps some people might think.
The simple act of sharing a space with your friends is something that f2f RPG's will always have, and MMORPG's will always lack (although as it happens I've played WoW with three party members in the same room as me, it was great fun). MMORPG's *are* however a social event, even if voice-only and/or text-typed communications create a different kind of party feeling than a game of D&D. A weekly game of WoW is in fact one of the ways I stay in touch with a distant buddy.
What f2f games give me that MMORPG's lack is the freedom to wonder what crazy adventures I'm going to get into next, and never quite knowing for sure where things are headed. There is an inherent predictability to a computer game which is not as satisfying.
There are no complex problems or wacky solutions in a MMORPG. The answer to most problems in a game like WoW is to use few, repetitive tools in known combinations against predictable enemies; the answer to problems in D&D can be almost impossible to predict (although admittedly Magic Missile tends to be the answer to a lot of questions directed at a mage

). Programming languages and tools, and the hardware that runs them, are going to have to change considerably before a computer game can encompass unpredictability and open-ended problem solving in any way that even comes close to what a few gamers round a table can come up with... but it will happen, one day, and I wouldn't be surprised if social gaming models are used as a basis for some of those changes.
I've never lost a player to a computer game: our roleplaying sessions are too few and precious for that to happen.
Computer games and RPG's fill two different niches in my spare time, but the two past-times still offer sufficiently different experiences that neither one excludes the other.