The visual novelty of Android versions seems to have died out a long time ago. You may get the new features, but there won’t be anything new to look at.

The theming decisions are really up to Google. I think complacency can be good in some ways, if you download from f-droid you’ll know that there’s a lot of discrepancies between the style and theming of apps. I think M3 is a good style and a good base for apps to build on, so there’s no reason to change it except wanting new.