I think DLC is only acceptable if it's produced after the game was released.
I don't think you should tier up a game that already costs quite a lot, when what seems to be offered is purely arbitrary. Also if they charge a sub, they have to deliver on the new maps etc, I don't see them releasing maps so often that are good and the game will become saturated with shitty maps. Valve have been working on TF2 with new updates since it was released, all of which are free (ok so the store isn't, but it isn't necessary) and the same can be said for the rest of their online games. Activision can afford to spend on aftergame support and care, they aren't exactly poor.
I have already spoken about class systems and dont wish to derail this thread with an essay.