I think what you're getting at is that there is no consideration of relative skills in ICM. For instance, if there are 10 players who each start with 1000 chips, ICM will tell you that everyone has a 10% equity, but you know that your equity is really something along the lines of 11.5%. Since what you are doing when you consider an action is comparing your pre-action equity to your post-action equity, and you'll be using your inflated equity both pre- and post-action, it probably won't make much difference.

Why don't you run through all the numbers on your hypothethical AK v TT situation under two assumptions: everyone has equal skill (so that equal stacks have equal equity); and you have a 15% equity bonus (and everyone else has a corresponding and equal equity deduction)?