I believe the original points of this thread has been already addressed, and well as it seems to me. However, I feel compelled to share my thoughts regarding this matter. I reserve the opinion that MATE is already fine as it is, because I consider GNOME 2 as finished (good) work.
Inheriting from a finished work and pushing it forward, I love how the MATE desktop has strictly adhered to the former's traditional metaphors across how many years. It is what appeals to its audience, and I believe modernizing in the sense that I got it from OP, would dissipate that appeal and so would the audience gradually diminish. Not a very good thing. It's like leaving your best friend behind, for no good reason whatsoever.
Or simply put, that removes the raison d'etre. So, what for?
With GNOME 2 being finished about 14 years ago, there are a lot of things to be done. @ericmarceau and @stephematician already mentioned some of them.
One that I'd like to add, and have struggled with numerous times before is the consistency of look and feel across the apps. I hold the belief that it's becoming more prevalent across GTK apps, particularly those using 4 and libadwaita
. I assume most of you have experienced that before, unless you specifically avoid or don't really need those apps. It just happens to be unnerving to open your desktop one day to find out that your apps revolted against your theming as if your aesthetic choices really are that bad.
But hey! If it is, no shaming, right?
I believe that this is related to the argument of a handful few that MATE lacks apps of its own, kind of in the same regard as Xfce. Though I find this immaterial against the fact that people are usually gonna pick up something along the way which they like better and often has more features. Such as in the case of a media player, where people I know tend to go with VLC.
Getting back on the topic, I believe MATE can do better in that regard. Just recently, Linux Mint had figured out how to work around libadwaita
in some of the GNOME apps they've previously downgraded. It sure is handy that they've also worked on Mint X on that regard. I'm pretty sure MATE and its loyal fleet could collaborate with the Mint team on this matter. Just imagine, how nice it'd be to have a desktop so coherent, Windows 11 would be so bashful of it lol.
TL;DR: MATE is a nice upkeep of already finished, well-done work. It'd be nice if they figure out the theming for newer apps, like Linux Mint did.