I've been trying to figure this out myself, it might not of met up with peoples expectations of what they wanted the game to be but it is successful. If we assume that the "under 1 million player, but way more the 500k" means around 800k, it has double the players of the #3 game "EVE" with 400k, and four times the number of players than the #4 game of "Rift" with 250k player. Now those games need a lot lower number of subs to stay successful, with there lower production costs.
I think the real issue is that EA expected to jump out of the gate with 12 million players like WoW had and take over the #1 spot, and it was never going to happen. WoW was a fluke, if it came out right now it wouldn't do much better that any other game on the market. It was just in the right place and the right time with a solid game.