Actually, D8 adds a few (optional) modules which add some nice UI flourishes to simplify things for administrators and content editors. The stock administration menu module has been greatly improved and made more user-friendly out of the box, and there's many places where you can now do in-place editing of content. Also, everything is responsive out-of-the-box, including the content editing forms.

Also, Overlay is gone. (Sorry about that showing up in D7. Some of us tried to stop it, but…)