Just think about it, you and a couple of friends are watching classic South Park or something edgy. And then, some person comes who's not even a fan of it, demands changes (censorship) or outright turns off the program. Just why do people do this? Why do they ruin everyone's fun?
Seriously, they are. This is by far the most important issue, if they made their asses fatter it would improve viewership. If they made the ponies thicc prudes would complain, which would only draw in even more viewers. Twilight Sparkle, the protagonist of the series has a fat ass, and her teacher Princess Celestia, who's ass is even fatter.
The main reason is uncanny valley. When something looks human but not quite. A perfect example would be a robot trying to mimic being human, it looks unsettling. It's somewhat insulting towards the ponies, you have Twilight Sparkle there a beautiful unicorn and you can't embrace her just because she's not fully in human shape, even though she has all the qualifications to be a sapient-minded
Blazing Saddles. The humor alone wouldn't be allowed as it is. It would be heavily censored and very "pointed" in one direction.
White Chicks.
Any of the Monty Python movies
Police Academy and Spaceballs
Tropic Thunder, perhaps the last movie that will ever use blackface.
Clerks 2
El Dorado
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They'd still make that, it'd just be full of more politics.
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Somewhere in the multiverse is an Earth that never experienced the masterpiece that is El Dorado, and my heart weeps for those sad children.
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Almost all Mel Brooks honestly.