Maybe they should add an educational history of film at Epcot as that is the educational park

(I'm not being 100% serious).
But in general the GMR was past its best. It could have been gutted and rebuilt, adding some new film classics and still celebrating the old stuff, but I imagine the chance of them getting all the negotiations sorted for this are a lot lower than 35 years ago and Disney themselves just don't have the classic live action films in their catalogue.
Also look at Universal Studios, that opened about the same time as Disney-MGM and pretty much the only original ride left is ET, things move on, tastes change, its not just about education, its about entertainment.