The new film got it right with both existing music for atmosphere and original music to bring the plot points, plus the added bonus of Muppet Show style song covers. Though I wish an instrumental of "Movin' Right Along" was used instead of Cars or whatever it was called.I see. Makes sense. Because if they hit with a film that does that, but does it the wrong way, it could further sink the Muppets into submission. The last few films before TM I didn't like very well. Wizard Of Oz, From Space, Treasure Island, and yes, I didn't like Christmas Carol either! The Time Travel thing looks sort of like it would be the same set-up as MFS. The Muppets live in a house together and sing one song while the others are stock licensed music. ****, MFS didn't even HAVE an original song! So, yeah, I see what you mean.
But above all, we need a movie where the Muppets play themselves. Stoller and the rest get that. The new blood gave a fresh perspective on the Muppets the existing staff didn't have, while the existing staff helped polish up the script with their know how of the Muppets. Win Win. A combination we'll likely see here again.