I think I know why GMC is perhaps my least fave Muppet film next to Elmo In Grouchland...it mostly just focuses on Kermit, Fozzie, and Gonzo...has too many human only scenes(which wouldnt be bad except they are all these super bourgious snobby folks that are unwatchable) ...and just doesnt seem to have any message or heart. And Charels Grodin, c'mon! He was great in M@WDW though.
That said, I think even the Muppets have stated on talk shows or q & a's, etc...that the Movies are just movies. Gonzo is not an alien. Piggy and Kermit are not married.
Even the Muppet Show I think they are just acting.
The only real testament to who they actually are, again are appearences(like the walk of fame), q&a's, interviews, talk shows, etc. Just recently Kermit referred to VMC as just a movie he's promoting.