I can kind of get by the Muppet Theater not being in the US, since as far as I can make out, it has always meant
to be there. Even with The Muppet Show the indication is that the Muppet Theater is some run-down, out of the way, forgotten cabaret kind of club, even though it was filmed in the UK (but then, so was Roger Rabbit's Ink 'n' Pain Club, Club Obi Wan, and many others). For me, it has always been based off-off-off Broadway, down a side street in downtown New York (or maybe the Bronx or Queens!?), which is also Henson connected, but just not in LA.
Good to hear the film really has been finding younger, genuine fans!
Interesting, though, to hear you thought it was melancholy throughout, since I mostly felt the opposite. I thought they did an exceptional job of keeping what could
have been a very downbeat story very up all the way through, save for the couple of obviously emotional moments. From Life's A Happy Song through to the end, I really did just have a very happy grin on my face all the way through, except for Pictures In My Head and Rainbow Connection, for the obvious reasons!
It must be approaching ten times that I've seen it now (we nearly just watched it again when some family came around this evening, but ended up with another potentially melancholy movie, Little Miss Sunshine, instead), and it still gets me in all the right places.
Of course, I've seen the other Muppet movies - the original Henson trilogy - many more times, but it's easy to remember they have their no so good moments too. I just think, for what these guys were up against, had to prove, and how the succeeded, it's a pretty great film.
And I don't really think Kermie left Piggy at the altar: even during promotion for that film Kermit kept protesting that it was an actor who "married" them. I think they were keeping options open, like "did they or didn't they?". Naturally they have been together in projects since then, but I think The Muppets works best as a sequel to The Muppet Show and those first three films - both tonally and technically - so it still keeps that potential storyline open.
Overall, for all the ways this could have gone in the other direction, Segel was as good as his word in being a genuine fan, and the end result speaks for itself.
BUT...be aware of this "Muppets returning to TV" stuff going about. Yes, the Jim Henson Company is talking to the BBC about making a show called "No Strings Attached", but this is NOT the return of The Muppet Show. Henson Co doesn't have any rights to the Muppets and this will not star Kermit and the gang. They've been very quick to jump in and pitch their show on the back of the success of the movie, but they're going to have to find an interesting byline, since although they're saying "from the creators of The Muppets", which is true-ish, they can't call their puppets Muppets or use any of the established characters. I don't think even the BBC quite know what they're getting at this stage, but it sure ain't The Muppet Show that we all really want back on our screens.