Very well put, PGoodwin! I am not so familiar with Msft products, but you're right, the designers here have no clue, they are just fiddling for fiddling's sake.
Indeed, I often get the impression, and especially with iTunes, that Apple likes regularly to shuffle the deck, to just take all the controls and functions you've gotten used to and put them in new places. Hide and seek. What was once a control-click turns into a drop-down menu. What was once in the menu at top of screen gets shoved into some other menu. And for what reason? Often, there seem to be nothing gained from all this. It's as if someone scrambled the syntax of a language everyone knows, just for the heck of it. In a word, maddening.
I, too, live by playlists, and the current iTunes is so dumb in its design that I really have to wonder what Mr. Design Himself, up in heaven, is thinking as he gazes down and sees the vaunted ergonomics machine he built crashing onto the rocks of mediocrity.
All of which is to say, for the umpteenth time, Apple, please give us back our multiple playlist windows. Pgoodwin is right; big-screen real-estate is getting wasted! Why, pray tell?