I'd argue that Unity looks much, much better on high DPI. I run it on an old crappy 1024x768 and a newer 1920x1080 of around the same size, and the icons/launcher actually look sane at almost double the DPI of the older screen. Unity makes the low-DPI computer look (and feel) like a toy, but I like it a lot on my new computer.

I'd agree with you if you're running Gnome 2, or KDE, though.