I get the want for the layered defense idea, and having just TR'd a bunch of melee toons I get it and think it works very well in heroics.
But in epics . . . especially EEs . . . this needs to be rethought. I absolutely hate that your AC is the LEAST important part of your layered defense. It should be the MOST important component as it's really the only thing defenders can get a ton more of over offensive builds.
What was the point of the changes if you're just going to jack up monster to-hit so much that it renders AC irrelevant again?