I think I remember reading an interview with Peter Linz talking about the 2011 movie a while back where at some point he said he doesn't even consider Walter the star of the film and stated that the main Muppets were.
Even though Walter's my favorite (well..
one of my favorites..), it
definitely wouldn't make sense if he'll become a more major Muppet than Rowlf and Scooter.
Of course he's a wonderful addition to the Muppets, with him being a Muppet we all can relate to. And, no kidding, I always thought before he'd mesh pretty well with the main Muppets. Sure, he's sweet and humble like Kermit and funny and childlike like Fozzie and daring like Gonzo, but sort of like what Peter said, I never imagined him being
more major than any of the main Muppets. Maybe since he also has a geeky personality, maybe it seems he'd be better off as part of the other Muppets instead, I don't know.