OS X :: Inconsistent UI In Mac OS

I always thought that Apple prided itself on consistency and aesthetics. So why is there inconsistency in the look and feel of between the windows of different apps and within one app itself? I'm looking at you iMovie. Scrolling bars can also slightly vary in width between apps. Personally I like the brushed metal. I understand that some people think that it looks "dated", but what does that mean anyway? The pyramids look dated too, but they're still cool. I don't like the grey & grey-blue look (iTunes). To my eye it comes off as cheap (Windows-like) looking. I also don't like the semi-transparent charcoal look, because I don't like light text on dark backgrounds...just a preference.

Also with that look there is a different feel. The red, yellow, green buttons are dark until mouse over. This decreases a quick visual understanding, and if you prefer cmd keys, mouse over is irrelevant. Shouldn't the OS enforce consistency between apps? Couldn't the OS allow the user to choose the look and feel of the windows across all apps? Not that Apple would likely allow that choice. Anyway, whatever the future holds for the UI, I hope it's consistent and aesthetically functional. I'll also hold out against hope that Apple offers 2 or 3 choices.