*Warning*
Long-winded rant:
It's a stupid design, they attempted (this being the keyword) to go for aesthetics, instead of being technically proficient, so they ended up failing on both fronts.
The main complaint with the Xbox was size, what does the 360 do? Deceive you. MS likes deception (MS points pricing is another example off the top of my head, not to mention the Core and the barebones Vista, it's all marketing), they bank on deception. There's no room inside the original Xbox, yet the HDD and power supply are internal.
The 360 gives you a giant fucking powerbrick and a non-standard HDD, which has been reduced to a glorified memory card, with the illusion of choice (removing a core feature of your previous system is asinine, imagine if the GCN came out with only 2 controller ports). Although the HDD being external has paid off, so you can keep it when you have to send your system out to be repaired. Yet it's basically the same size and weight as the Xbox, not to mention being worse quality and louder than a console should ever be, they completely ignored the REAL issues.
There's nothing elegant about it, it's big, loud and clunky. Being vertical looks better, but I certainly don't trust the 360 when it's vertical, so that's kind of useless. When it's horizontal, it lacks a place in the front for grip. I have fun with it (it's all about the games after all), but I'll be damned if it's not the one of worst designed consoles out there and ironically it's modeled after a dead person, how fitting.
"Double concavity"
"Derived from an inhale"

For the Xbox 3, why not make a console that's not only reliable, but one that isn't forever gimped by a cheapass marketing decision?