I dunno, how do we generally feel about people who destroy or fundamentally alter works of art for mercenary reasons?
So the question becomes - are theme parks art? We've gone through this with film, TV, comics, video games - and I suspect the answer for theme parks will be the same as it was for those.
I don't personally feel that this is the same thing as film, TV, comics, or video games because by nature, theme park rides are not permanent. Long lasting, sure, but not permanent. They're not going to last forever in the same way that a film can live on, or a TV show can live on, or an album can live on. I absolutely believe they're art, but I also cannot pretend they don't have an expiration date.
What is unique about this medium is that when one piece of art reaches the end of it's lifespan, it can be replaced by a new piece of art. The debate that gets waged here is whether or not that new art is of the same caliber as the old art, and that is where I say there is no right or wrong answer to that question. Someone isn't wrong for liking a new ride just as someone isn't wrong for preferring what was there before.
We can argue all day about it, but that's just the simple fact of it all. No one side is objectively correct because there is no such thing as objectivity when it comes to what people enjoy. It is purely subjective in every possible way. There is nothing on this planet that everyone universally derives joy from.
MuppetVision's film is being preserved. That is the piece of this particular artwork that has no expiration and will live on well beyond the building it was shown in. The attraction itself though from the moment it opened had the same ticking clock that every theme park ride does because they simply cannot and will not last forever. I know you will disagree with me on that.
But I truly look at theme park rides like a theater production. From the moment that production opens, it's a ticking clock to when it closes. Yes, someone somewhere else can stage another version of that show, but it's not the same. It's a different version. That one show will only last as long as its run, and when that run ends, that particular show is gone for good. What other version comes after may not be as good as the one that came before it. What entirely new show moves into the theater once that show finishes its run may be better than the show that was there before. That's just how it goes. These things just don't last forever.