Well pretty much everything the OP posted in just a straight up downgrade in UI. Harder on the eyes, takes up more screen space and does not effectively convey information.
I’m actually pretty fine with the current UI, it displays what it needs to and is easy to get out of the way when you need to. What i would like is more keyboard commands, especially shortcuts for doing fuzzy searches so you can easily search the scene, project and components lists with one keyboard command. Something like the shift+shift menu in JetBrains ides. But even this can easily be added by the user since i was able to add some editor scripts myself that i use for quickly searching and switching between scenes, or focusing certain assets used a lot on a per project scope.
Also the Header, MenuItem and ContextMenu attributes are a really useful and easy way to improve the UI for your project.