I don't mean to question how big of a fan you are or nothing like that, but I never heard of a Muppet fan that doesn't remember the Muppet Movie. It's not excatly a "modern movie" as it came out in 1979, so needless to say the songs aren't "modern" either.
I don't know why you're lumping in "the magic store" with those songs,
, or really why you brother to mention "modern music" and you're dislike for it. The Muppets have already done a little rapping have you seen the Coolio episode of "Muppets Tonight?"
It happens classic characters like Muppets are always going to do whatever to seem "hip and cool." I don't think they'll go to the level of making them sing some god awful "emo" songs, but stuff like signing rap or modern pop songs like they did in "Studio DC: Almost Live" is going to happen.
Back to MFS, though, I don't care for the whole Gonzo is an allien idea. I think it was more or less a cheap answer to a question people have been wondering for years. I like that Disney upon owning the Muppets have dropped the whole "he's an allien idea" and turned him back to an "whatever." They didn't drop it all together though, they use that as a theory as to what Gonzo could be, which is fine.