I use like 30 addons in all, here's what it looks like:
http://i.imgur.com/RUkS6Lo.jpg
I rearranged everything so I get the info I need, WHEN I need it while minimizong clutter. My UI is infinitely more efficient than the default UI, not to mention it's more visually pleasing. In my opinion, people who randomly install addons and get a UI like
this are no better than those using the default UI.
Really, the problem with the default UI is it's layout. With minimal changes to buff/debuff tracker, unitframe position(And raid frames for healers. God, if I ever find another healer using default frames in a raid I'm going to slap him) and CD tracking, the default UI is usable.