Alternative hypothesis: Those two games failed because they svck.

Plus, at least one of 'em had stupidly high development costs for what it is.
While it is a very competitive market out there, and people tend to go where the freebies are, remember that designing for free-to-play often means charging for things that players used to take for granted in subscription-based games. You can see this in many hybrid F2P games, where freepers are seriously restricted in what they can do relative to subbers. And, of course, all the really cool stuff often gets introduced in cash shops, whether or not you pay a sub.
I'd much rather companies design essentially sub-based games, with budgets that
realistically estimate their target audience. If they want to add a limited F2P option on to that, more power to 'em - but I really don't want the game to be designed for free-to-play.