Earlier quoted context omitted.
Second rate UI? The IntelliJ UI is pretty great, it's very well optimized and has a billion features. I don't think any new IDE would look significantly different. There are only so many ways to do buttons, scroll bars, trees and editors.
I don't actually mean IntelliJ in particular, but Java having its own UI kit. Nothing looks or feels native on any platform. I've heard something about a graphical widget kit that emulates native on Java, but as far as I can tell IntelliJ (and most Java apps I've seen) don't use it. Though since you mentioned IntelliJ, I find its UI pretty hectic too, a hodgepodge of 90s-style MDI and modern tabs and split panes. Som…
In an attempt to be helpful, in case you don't know about it, the shortcut ctrl-shift-a brings up a quick search box of every action, pane, or other ui in IntelliJ. You don't have to drill down to get places, you can just jump there directly.