To make money, F2P game devs need to add "features" that suck, and they need to hide content behind a paywall that ends up costing more than a subscription or retail box to bypass.
F2P economies require adding busywork/grinding to the basic game design so there will be something to pay to bypass.
F2P game devs are forced to make their games less good than they could have been if they'd used a subscription or retail box model.
P2P games give you all the content up front, and everyone is on a level playing field regarding access to equipment and abilities. There is no artificially inflated grind put in place to intentionally frustrate players. Devs are not forced to make their game less good for the sake of the economic model.
I've never played Path of Exile, but I guarantee it could be even better than it already is (which is different from saying it's a bad game).
Edited by willis888 - 2/16/13 at 9:38am