As far as how the Emperor looks, the new one was shot over 20 years later so obviously you can’t fully replicate the Emperor’s original look and for that reason I’m willing to accept it.
No, they didn’t need to replicate it perfectly. But there’s no reason they couldn’t have gone for the same aesthetic. A more makeup based approach instead of thick sort of reptilian-looking rubber. And although Ian was over 20 years older, this isn’t exactly a role where an actor’s age will prevent them from being able to look the part. Assuming he doesn’t gain a ton of weight, he could probably be made to look the part when he’s 90.
But I agree with the rest of what you’ve said.