I wish they did have this option for NA since it gives the option for the casual player to pay when he/she wants and not be tied into a monthly recurring plan. The subscription fee will cater to the hardcore player since it is easy to use up 92 hours (@ $7.25) in a week with all there is to do in this game.
I'm really looking forward to open beta since I can bask in the world of low latency and to further tune my Cleric macro's and PvP strategies. In China Retail, Aion played very well with a ping average of 400-800ms. With a solid ping in that range, I wasn't able to notice any lag at all unless I was actually watching Genna's screen (3 feet away) and seeing that my char was on a delay on her screen.