First of all, it's an odd definition of story.
Not really. It's narration. Fluff. Reasoning. The part that does not describe the rules effect as much as it describes the fairly arbitrary process by which that effect is achieved.
Colour feeds into mechanics which produce colour which feeds into the mechanics again in a cycle.
Ideally, IMO, yes. But in 4e, there is a clear line drawn between the two. That clear line is part and parcel of the balance in 4e. It doesn't matter if it doesn't make sense, in "color" to, say, knock an ooze prone -- that's what the rules say happens, that's what happens. That's one of the big ways that 4e dodges the "accidental suck" phenomenon that plagued 3e: you can sneak attack undead now, because it doesn't matter that they don't have beating hearts and lungs, and thus rogues are useful no matter what enemy you are facing. The rules trump the fluff. After the fact, you can apply logic to the rules to fluff them into making sense ("ah! even undead have weak points and structural problems that can be exploited!"), but that's just kind of rationalizing.
That's part of what "power stunting" threatens to disturb. 4e tends to say "This is the rules result you achieve. However you want to describe that is fine, but don't mess what the rules say you get, even if it doesn't make sense at first." That's consistency, that's portability, but that also doesn't accept rules-results innovations very comfortably. You're messing with what the rules say you get in the opposite direction: giving them MORE. This threatens to stomp on the toes of other powers and other roles and other classes, if it's not watched.
Colour: The ooze shudders and trembles and takes time to pick itself back up again before forming a psuedopod to slam you with.
See, that's a perfect example of the rationalizing I was talking about. No, it doesn't make sense that a mobile puddle has to "pick itself back up again," but if that's what the rules say happen, that's what happens. This means that your power is still effective against oozes, which is great from the perspective of consistency, but makes the whole "color" --> "mechanics" progression run in reverse for a minute. It becomes "mechanics" --> "color."
Stunting works in the opposite direction from that. They describe a story, you give a mechanic. Only with powers, there already ARE mechanics, and these mechanics are things that you shouldn't generally mess with (to the extent that they will reverse the progression if need be to preserve themselves). If you do mess with them, you're essentially breaking the structure of the powers system, which isn't inherently bad, but carries that "juggling fire" risk I mentioned.