The main influence so far has been enabling smaller window sizes for gtk+3/libhandy apps, which is good for all users especially those on older, lower-res hardware. Hopefully libadwaita can get forked into something like a libhandy equivalent for gtk+4, that otherwise preserves sane defaults doesn't enforce their silly "flat" theme choices.
>The main influence so far has been enabling smaller window sizes for gtk+3/libhandy apps
I don't think so, touch targets are a lot bigger. Using the default theme for both a KDE App with equivalent functionality will take a fair bit less space than a similar gnome app. Of course I think plasma mobile uses a theme that makes the touch targets bigger...
KDE also manages to get a lot more functionality into their similarily sized windows. Take a look at this page showing comparisons:
