I don't have a major objection to micro payments for a boost, or even for new content, DLC or otherwise.
What I do have a problem with is the constant, in your face offerings to purchase this content. In particular, LOTR really gets at you all the time, with the trick buttons and trap questions and you end up with that damn store window open again.
If you're going to implement this kind of thing, please keep it out of the game, and restrict it to the splash screen, or ingame menu or better yet, browser and account website.
Continuity is really important to me, new content needs to be seamless.
Saying that, following the LOTR model of offering subscriptions or micro payments is probably the best place to be.