Not necessarily, it isn't a proven fact that MMORPG's should only be on PC's and if they were on a console, that'd be a failure... I myself would like to see an MMORPG for a console... Oh wait, they've got one.. FFXI, and from what I've been told, the console version is just as good as the PC version.

What else, there's Phantasy Star Universe, whilst a bad game in my opinion, apparently the online play is pretty good.

See, mmorpg's on consoles aren't unheard of, and in the cases they ARE on console, they aren't terrible...

Yep.
Consoles are great for the fast moving games. PC have been used for most of these types of games because of the keyboard in all honesty. They can put less objects all on one key. Whereas with a console, options have to be crammed into one or two buttons.