They don't have much of a choice. They bet the house on liquid glass and need to keep up appearances.
How? If they reverted to the previous iOS and macOS designs, Apple would go out of business?
What are you basing these claims on?
You can look at Apple’s own published consent regarding Liquid Glass development. It’s very evident that it was thoughtful and involved.
I think it's more realistic to expect that they're going to stick with a UI officially called "Liquid Glass" for the next decade, but it's going to go through some serious iterative changes in the next couple of years -- probably much more than it would have were Alan Dye still around.