To me, creating a MMO looks like one of the most difficult thing you can imagine. There's almost no finished (or even beta) free (GPL or so, I mean) projects on this subject for example. It would require a huge and long work for an entire team.
Raydium needs more hands, for sure. But IMHO, the best we can do is release more polished and finished "simple" games. It's the Raydium way to do it: simple. ManiaDrive was a real proof of this for me: this game was downloaded 230 000 times so far, appears quiet often in top ten linux games and so on ! And we're talking about something with less than 3 000 lines of code.
In short, for me: simple concept + simple but complete gameplay = super combo !
But I wouldn't be upset if a MMORPG project was built with Raydium !
PS: IIRC, you own a PS3. A game is available since a few weeks on the Playstation Store called "Pixel Junk Racer" (or someting like that). I would like to have created this game

It's exactly what I'm talking about: the concept is uber-basic, but 100% fun with a simple gameplay and a lot of different modes.