It's Gray for a reason, if you're trying to concentrate on color correction and the finer details of your edit, you don't need anything distracting you. The most important thing to look at is what's in your canvas & viewer.
That said, FCP and the pro-apps in general are in need of a massive UI overhaul. There is a distinct lack of uniformity and that needs to change. This isn't just cosmetic, Color, while being very powerful, needs dramatic UI changes to make it a lot more useable to the regular user (inclusion of sliders, removal of the need for a 3-button mouse configuration - even though there's ways round it)
It could go on and on, I would think that an update will follow after Snow Leopard and Quicktime X, both of these will go a long way to re-writing the core of FCP, you'd like to hope that UI would follow.