I admit I don't fully understand the premise but I'll try to paraphrase as best I can and give my thoughts and you can tell me if I am way off base.
Everyone is doing their opening burst and generating 90% of that enmity themselves but then the remaining 10% that would be generated (numbers here purely for example) could be taken by the tanks with some sort of ability and thus a MT would have his own enmity generation and then have 10% of everyone else's as well? Sort of like everyone casting a weak Shadewalker all the time?
I feel like while this might eliminate Diversion as a skill it just puts all the responsibility for enmity management on the tanks which frankly seems like it's letting the rest of the party off easy. Plus I would assume this skill would be a dps loss in some capacity as most enmity generators are which then leaves us with the additional issue of tanks not wanting to take any more enmity than they need to. As a dps that sometimes creeps up aggro tables at the wrong time (and a part time WHM who does so seemingly all the time) I would say this is asking for trouble, specifically with situations where you have less skilled tanks who don't know how to hold threat.
Right now if I actually use Lucid on CD I won't pull off of a tank in single target and I do respectable damage as a RDM, assuming I was able to Diversion for my opener. Leaving that management up to tanks would likely see me tanking a lot more dungeon and normal raid bosses than I would like to.
I don't know. Perhaps I've misunderstood your intent but to me this sounds like something that would make tanks lives harder which isn't what we need, or it would be overturned and trivialize enmity management even more than it already is. I agree enmity as a whole could use a fresh coat of paint but I just don't know if this is that paint, I'd like to continue to see the responsibility shared over the entire party as to mimic the rest of the potential responsibilities like mitigation and dealing damage.