> I think there's an obvious and more general question here to be answered: if a piece of software is good enough, namely, it "disappears" when you are trying to do your job, then why bother to change it?

I find I care about the applications I use: my IDE, git client, console, and the various web apps I use. I don't so much care about my browser UI, as long as it gets out of the way and shows me what URL I'm on and renders the page.

Likewise, I don't care about the UI of the OS itself, as long as it does its job properly: lets me start and switch between apps, connects to wifi, manages the display power, and sleeps and wakes up.

When I'm looking at the computer screen, I'm looking at what I'm doing, not the UI chrome. Even now, I'm only paying attention to this comment text box and your original message.. Everything else -- all the other tabs I have open, the visible bits of the OS, the other window open on my next monitor -- all blends into the background and gets ignored.