In my view, what causes a Michelle Kwan to say that Yuna has "changed the face of figure skating" is that she is perhaps the first (but not, I think the last) ladies skater to have successfully juggled the arcane COP equation such that the outcome approaches maximization of the current physical/technical potential (as codified in the technical score) without sacrificing a truly high artistic level.
IMO, attempting to strain out and isolate overall artistic quality (as opposed to comparison of individual elements or skills, which haven't changed) specifically to make valuative comparisons with skaters who performed under different conceptual regimes (eg 6.0) is difficult at best, and wildly misleading at worst.
It would be akin to taking two athletes, putting 20 pound weights on the legs of one while hanging them to the wrists of the other. Relatively speaking, the former won't run as fast, and the latter wouldn't make a good boxer. In my view, it is equally erroneous to say, on the one hand, that Michelle didn't have it in her to jump great 3-3s as it is to say that Yuna's artistic achievements cannot at least be compared to Michelle's if, in some figure skating heaven, we could see both at their peaks and training and performing under the same parameters.