Maybe if you have your machine sitting out for public display in your house/business and want to use it as a talking point. However, mine's tucked away in my office with loads of other technology piled around it which I need to use as part of my job.
I get the point about the aesthetics of the things around you affecting your state of mind and whatnot. I love seeing well designed products (both hardware and software).
However, given a choice, I'd much prefer having more attention to detail paid to performance than aesthetics. Because, when it comes right down to it, I get a bigger smile on my face seeing my machine crunch through code faster (so that I can get out and enjoy other parts of my life more), than I do seeing a couple more inches of my desktop all day. :)