I'm not comfortable with the notion that people are somehow "dumber" now; there really isn't any evidence for that. Shorter attention spans? Maybe, but I'd argue that putting all the blame on the audience is a means of taking responsibility off the organizations, businesses, and other institutions that, as said earlier in this thread, "seek out" the lowest common denominator rather than using their creative advantages and financial strengths to do something constructive and positive for all.
As for the larger argument concerning EPCOT, part of what frustrates me about the move toward IPs and various toons is that I really enjoy a lot of those things, but end up kind of resenting them as they take over more and more of the WDW experience. I don't like feeling that way; I don't want to "resent" Mickey (or whatever the change might be now) for taking over Great Movie Ride, I don't want to "resent" various IPs for getting in the way of more creative visions for EPCOT, I don't want to "resent" meet and greets for eating away at space and funds that could go toward presenting more varied offerings to the public rather than falling back onto the same formulas aimed at the same audiences over and over again.
Everybody rightly acknowledge that some level of change in inevitable in the theme park experience, nobody argues that, but even as a child many of my favorite Disney World experiences were the ones that didn't feel 100% "Disney", know what I mean? EPCOT didn't have Mickey and pals for awhile; MGM had them as compliments to the overall experience, not dominating it; the resorts did some interesting conceptual things and, again, mostly used Disney characters as a compliment, not as the heart of the experience. Heck, early WDW largely marketed itself toward young, childless guests; kids were obviously welcomed and thrilled with the place, but they weren't the only market being catered to. Again, even as a child I really appreciated that.
We keep coming back to it, but yeah, "blessing of size", it'd be nice to see them use it more to vary up the themed experiences.