I can't stand having windows open when you can see other apps that are open or the desktop in the background. It doesn't help that I have ADD...I get distracted sooooooo easily. I always have tons of things open, too ("power user" or just disorganized?).
I do see the value of being able to have multiple windows open and accessible, e.g. for graphic designers using photoshop, illustrator, the web, etc. simultaneously. Also, I suppose it would be annoying to have a bunch of gray space filling up your screen on sumpthin' like one of dem Mac displays der (talk about real estate!).
However, they could at least give us the option to block out the background clutter or leave it as is. Perhaps they need to add a blue (purple, or whatever color) button at the top left that would maximize to full screen. No need to change things dramatically...just have the option available.
I've been using Macs since OSX came out (give or take) and that is one thing that I still can't get over. Is this too petty???