Bear in mind that higher resolution display != smaller UI elements. It gives you that option of course, but for most people the benefit is that fonts, icons and images look so much crisper and more readable.

You're definitely not the only one who thinks it's overkill. I've shown my retina iPad and MacBook to a few people who don't get the fuss at all. I guess this reaction could be due to a) not caring much about aesthetics, b) bad eyesight, c) not spending the time to get familiar with it and use it for some actual tasks. Myself, I think the screens are amazing, and each time I go back to my 23" 1920x1080 monitor is a little painful.