DDO just went FreeToPlay. Very good news imo especially because I never in a hundred years would have played this game - now, I will. What could be easier to understand? I'm positive that the same will be true for thousands of other players too. This pricing model just WORKS for gamers and developers alike.
We're right now on the edge of a huge shift in the industry and starting to see more indications trickling into the mainstream. What we'll end up with once the transition has completed in a few years time, is more gaming choices for the player to try out without having to resort to piracy. There are very few reasons NOT to at least try a F2P game, and once you are trying it then it becomes the developers job to get you to stick around and play for a while.
The pricing model of the future mainstream will certainly be Free to Play in my opinion, it is highly successful already in dozens and dozens of games right now under the radar, and we'll continue to see more and more companies dipping their toe into the waters to see if it's hot enough. If done right, it IS.