In my experience, this only really kicks the hardcore players in the ass. I play sasually, and the various rewards given as time progresses work well to offset the non-pay penalties.
SWTOR does this well. Sign up for a secure key app, there is 100 coins a month. Progressing in levels and achievements in game nets you xp boosts and such. Quest rewards are the same for everyone- and often it is XP or power boosts as well. Spend the coin to pen pay-only areas for a week, go play them that week. if you like it open them again next month. Pop your XP boosts and you play a level game with a subscriber. Or, as you get high level, buy those market items from the auction house for game money. When you are sitting on a couple million with nothing else to spend it on, why bitch as a 10 pack of major XP boosts for 10k? Or a token to open restricted areas for a month for 100k?