While I really liked the idea of Hellgate: London the subscription model they attempted to push was a huge turn-off. It was more like Diablo/Diablo 2 than it was an MMO, very few people playing together in an instance. This means that it had comparable costs of Diablo 2 with battle.net.

The subscription model looked more like a cheap way to squeeze extra money out of players. Charging extra for additional content (like Lord of Destruction for Diablo 2) would make a lot more sense.