See the cat? See the stripes?
Remember back to the public beta, and 10.1 and 10.2. Lots of stripes. Remember before the Finder used brushed metal? Remember how even title bars had stripes—and how the stripes everywhere were very pronounced?
At the time, of course, OS X got high marks for the beauty of its interface.
The reduction of the stripes and gratuitous transparency are, to me, among the most important changes that Apple has made to the OS. As with some of the other OS X improvements between the public beta and 10.4, celebrating this is kind of like thanking the bully for not beating you up anymore. It doesn’t really make sense, but you’re so happy that the bruises are healing.
Although I remember some vague claims years ago that the stripes made Aqua easier to use, I never believed them, and I think a true study would find the opposite. I know that OS X doesn’t tire my eyes out the way it used to. But, at one time, Aqua was the stripes, and we were told things like this:
The proper appearance for window backgrounds on Mac OS X is the pinstriping. Failure to adhere to this means your product won’t be a full class citizen from an appearance point of view, not to mention the fact that Aqua interface elements (buttons, checkboxes, etc.) were designed specifically to exist on an striped background and don’t look right on other backgrounds (including white).
—John Geleynse, Apple User Experience Technology Manager, 2001-05-18 message to the now-defunct Apple Human Interface Developers mailing list
My theory is that the stripes were a gimmick to encourage carbonization by making Classic applications look “bad.” Now that most people no longer use Classic, and Jonathan Ive is into solid-colored hardware, the stripes no longer serve any purpose.