I personally think that the shift in "design" in Apple has gone from "well-designed" to "stylish design."
The truth is that the swoopy, indulgent and over-the top blue G3 Power Mac from 1999 with its teal and white color scheme and bold "G 3" graphic was better designed than the minimalist Mac Pro. It has something to do with a unique case design that hinges the side down, with the mainboard built into the door so that the entire thing is laid out there ready to service. No side-panels popping off, no removing drive cages. It's just right there. The Mac Pro looks like a nightmare by comparison with everything shoved up inside so as to not interrupt the smooth chiseled lines or whatever.
The OS fortunately has followed a minimum of minimal. Aside from streamlining, OS X has gone through few changes since 2002 when 10.2 was released. As for its "design," it's a combination of NeXTSTEP and pre-System 7 Macintosh. Its appearance keeps getting tweaked, so there isn't much to say about that. Appearance does not equal interface.
But then, I couldn't care less what the box looks like. At one point I used a broken Powerbook from 1996. It had no screen so I had to hook up a monitor to use it. In 2002 my first iMac croaked. Again, dead screen. So I ripped it to shreds and ran the bottom half without the screen, using a VGA monitor plugged into the back. I had to drape a sheet over it for a week to keep dust from getting inside before I finally made a cover for it. How the box looks is immaterial as long as what's inside of it functions properly.
So I'll totally agree that Apple's "design" isn't for everybody. I'm one of those people. I like the software, but hate the hardware. Leave it to fashion to say that a detailless gray box is stylish and not bland.