I had to install mate themes myself too as I do not like Yaru. I won't complain as long as the features are there, but could move on if they disappear.
I sincerely hope I'm wrong but I'm starting to see some signs on the horizon that we may be headed that direction. It's one thing to need to install additional packages. It's a pain but that can be done without issue. It's an entirely different issue when things start breaking as a result of being removed from the base system.
For instance: I used to simply use the Ubuntu-Mono-Dark icons. They were basic, classic and worked well. If you were to install Ubuntu-Mate 20.04, or even 18.04 and earlier, you could use that as the default icons without issue. Ever since 22.04 suddenly using that as default theme causes some icons to no longer have an icon. I'm talking about base packages like Mate-Tweak. The removal seems deliberate since these icons were present without issue in prior releases. It makes no sense for them to be removed now. But if I want system consistency I need to use a Yaru version of the icons. Or be willing to manually edit icons for multiple applications.
It's kind of neglect that made me so anxious when Traditional Desktop was demoted for Familiar back several releases ago. Either people would start missing things or they'd start creating papercuts like these in effort to boost their preferred settings by making the traditional settings look poorer or more of a hassle by default.