Except, in terms of DVD release, they hate those guys as well. Sure, they released the full 90's Fantastic Four series, 90's X-men in odd 2 disk volumes, and the Avengers cartoon before the current one in single disk volumes... but where's Spider-Man and His Amazing Friends (though it is on Netflix), 80's Incredible Hulk, 90's Incredible Hulk, and the original 60's Spider-Man cartoon (though, who'd want that one). Sure, there's a lot of Marvel stuff Disney can't get the rights to, like the HB produced FF series and some of the Sony made Spider-Man cartoons (but Sony still can release those, so...). But there's indeed a lot of stuff they haven't released on DVD yet. Heck, even their current Marvel cartoons only got crappy single disk releases.
And who wants to bet Disney isn't going to even touch Droids and Ewoks? I don't think we'll see Rebels in the same season sets Clone Wars was either.
Bottom line. Disney hates releasing season sets of anything. Even cash cow Toy Story didn't see a Buzz Lightyear of Star Command release, Winnie the Pooh's new Adventures cartoons saw sporadic 3 episodes on a 15 dollar DVD, and that's the one thing you'd think they would have released by now. Why do you think all the Disney Afternoon DVD's stopped half way, and The Tick had 2 incomplete seasons culled from Comedy Central reruns (read edited)? Even their own crappy 00's era sitcoms had to be rereleased by Lionsgate (as if anyone wanted them).
So it's not a Muppet specific problem. heck, the Muppet ones they did release had a tone of more care than any of the DA cartoons I mentioned. They couldn't get Jim Cummings to sit down for a few minutes to interview him?