It's a good thing Windows doesn't really need to sell itself to much of anybody; after nearly twenty years of the old logo's incarnations, it's pretty big to just throw it all away. A large portion of modern consumers associate Windows with the four-colored 'flag' design, and this is a pretty dramatic shift.
It also worries me that they insist that the reasoning was to put it in line with the Metro design, because as of right now I feel like Metro is Windows 8's greatest misstep. I'll admit I haven't tried the demo versions yet, but I didn't care much for what I played with of WP7, and it certainly isn't working on the Xbox. I don't feel like it'd make a good PC interface, and I feel like that's what they're overlooking when they talk about tablet integration on Windows 8. I'm sure you can turn it off if you don't want to use it, but why make it a standard in the first place?