Even if it wasn't a sequel, direct or otherwise, they'd still call it one. I'm pretty sure that Disney coerced them into making the film an actual sequel when the writers have been on record saying they wanted something more disjointed. The happy medium was lampshading the fact it was a sequel with barely any of it actually connecting to the first one.That's what I was saying previously: each of the Muppet movies were their own, one-off, stand-alone feature - they weren't connected to each other via a plot thread, or a hook, or anything, they each had their own self-contained story. I think that's just about the only problem with MMW is that it was a sequel - it continued where THE MUPPETS (2011) left off, and didn't hide the fact (nor were they shy about the Tom Hanks making TOY STORY 4 joke). I mean, sure, it's just my opinion, but I think MMW would have been a whole lot better had they not done the whole, "We're Doin' a Sequel," bit.
As for the DVD's, if that's truly what the public wants, the nostalgic T-shirt wearing, Robot Chicken and Family Guy cutscene, Sesame Street/Muppet Show confusing casuals want, I don't think the movie was in anyway an indication of the popularity of the franchise. If it's still a music rights thing, I don't see why Disney can't announce a list of the songs stopping them. At least then we can growl at the Monty Burns types that own them. Wouldn't be surprised if some likeness/celebrity rights issues are in the way as well. All I know is, nothing was stopping them with Star Wars characters before, and darn straight nothing's stopping them now.
EDIT: I forgot to mention that Disney did indeed have plans to release Goof Troop, the rest of Talespin, and Ducktales the Movie to general retail after having these available for Movie club. They're clearly vanilla releases (I'd rather the term be sweet cream releases as vanilla is indeed a flavor), and well along the lines of the rest of the TDA "Oh Well it's something" DVD's. I'd love to hope this means that the rest of Darkwing Duck and Ducktales are in the pipeline.