The somewhat bizarre thing to me is that D&D has always had these mechanics - its to hit and damage rolls are the most obvious examples (what does a hit with a roll of 6, that does 12 hp damage, do? the GM just makes it up - the system only provides an answer if the damage reduces someone to zero hp). The GM deciding that on this occasion the 12 hp of damage mean a bruise to the hip, but next time narrating it as a stinging blow to the ribs, isn't houseruling! (And it's ludicrous of Justin Alexander to suggest otherwise.) S/he is playing the game, by adding in the narration that the system calls for.
The difference is that in nearly every case in 4e, the use of a power has a secondary effect that is 1) hard-coded mechanically, 2) strictly enforced in the fiction because REASONS (whatever fictional reason you choose), and 3) tied to an overarching metagame resource structure (AEDU) that
in and of itself poses problems for fictional narration (I've seen comments even from 4e fans that martial dailies occasionally strain the limits of plausibility for the fiction).
4e seems to differ only in (i) generalising them from combat resolution to the skill system and the martial resource suite, and (ii) putting more of them on the player side (no GM, presumably, is going to ad hoc the narration around every player's use of an encounter power). Obviously some people don't like it, but that's all they have to say. There's no need to build a great pseudo-theory around it. Ron Edwards had already completely analysed it more than 10 years ago (and more than 5 years before 4e shipped).
And this is a big deal.
Here you make it sound like a trivial thing----"Just let the players make up the narration." When I'm playing an RPG, I don't want to be making up the fiction for what just happened every single combat round, for every use of every power. I want to be in the head of my character. Energy spent trying to couple the use of a power to the fiction
is wasted time in the game for me, and dramatically reduces my enjoyment of and inducement to play the game.
When the fiction is decoupled from the mechanics, SOMEBODY, AT SOME POINT has to make up the fiction. And 4e's approach to "fiction creation" at the level of using powers is far, far too granular for my taste.
Furthermore, based on the situational use of a given power,
the fiction for that power has to change. I've seen numerous, numerous times where 4e proponents say, "Well, just because you used that martial encounter or daily THERE, doesn't mean the character did the same thing in the fiction when they used it HERE."
And why do they say that?
Because if they don't, the fiction breaks down to levels that are unacceptable even to them. So I can't even make up one single fictional narration for a given power,
I have to recreate the fiction for that same power multiple times throughout the course of even a single gaming session, otherwise the "fiction" starts to feel like......well, dare I say it......a TACTICAL MINIATURES GAME instead of a shared dramatic milieu. (Yup, I dared say it.)