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I think I have part of the answer, after having tested them both very briefly.
Both are still using WoW as a model, without much improvement as far as I saw.
Apart from this model dying, there is, however, a deeper lying reason:
It just feels flat to wield a firearm and not being able to actually aim and shoot it. The tab-targeting works just as if it had been with a fantasy game, but because the envrionment is so close to first-person-shooters, the artificiality and the removal of you from your character hits home so much stronger.
You become more aware of the mechanics surrounding tab-targeting than you otherwise would.
The feeling you get is quite flat and one of powerlessness. You don't have that satisfying feeling that you have from an FPS after you shoot and you see the target fall over. Once one piece of the puzzle falls apart, then the players begin noticing the others so much more.
Tab targeting and firearms is a bad combination, that doesn't fall through in the same way in a fantasy styled game. Why? I don't know exactly, but maybe because we got used to the fantasy-style from singleplayer games before the MMO's? In my opinion, it is the inevitable comparison to FPS'es because of the graphical similarities that makes the illusion fall and the game with it.
My theory of course