Kids MMOs rule the f2p market.
Seriously....
Look at Wizard101, it has a plot and its really good!
Pirates online, a plot and has a point of leveling and great updates!
Free Realms, seriously...Its perfect for a f2p game and it acts like a p2p game.
Club penguin, its decent for little kids...
I mean, i dunno why, but kids mmos are actually ruling the f2p market...Their really good games actually and better than these korean grinders...That's one thing that Korean/japan/ or what ever, doesn't have.