I agree with a lot of the posts here, but it's a tough question.
I think the simple answer is that EPCOT itself doesn't really have an identity right now. It doesn't know what it is. It's a celebration of world cultures, of nature, of discovery, and of, um, celebrations (all with Disney IP integrated into it)? Aside from the "celebration of 'celebrations'", I think I would applaud them if they were building a new theme park based around these ideas. For the purposes of this post, let's pretend they actually built a theme park from scratch based on World Cultures, Nature, and Discovery. We'll call it "Disney Destiny Park" (just made that up, doesn't matter what you call it).
EPCOT had an identity and a purpose back in the 1980s and 90s that doesn't fit in well with the theme park expectation of today. It wasn't your typical theme park. There were no thrill rides until Maelstrom (thrills debatable) and Body Wars. But EPCOT still thrilled people with the tech/countries/optimism. But as the theme park industry expanded in Florida, EPCOT became the boring park. So it changed, and I understand why.
But it's just hard to watch it change from a very good not-really-a-theme-park park to a lame version of "Disney Destiny Park" as I laid out earlier.
So what is it? Something that can't really be fixed. To really do what they're trying to do, they'd have to bulldoze the whole thing. I don't want them to do that, and neither do they, so instead we get whatever this is: Remnants of what was once the most unique theme park experience in the world, with glimpses of a cool concept for a modern theme park that can never be fully realized.