A US Saturn isn't really ugly, its just way too plain. All the (few) details it has just blend into the blackness.
Both my cars are black, as was my previous car. Half my clothes are black as well.
My problem with black US systems usually has to do with them being changed to black just for Americans. Its true that a lot of people in the US love huge black things (ie: Cadillac Escalade) and its true that some of us buy brown underwear "just in case" not all of us are like that. I think the PC Engine looks great the way it was designed originally, and I have no urge to buy a larger, blacker, TG-16 just because I live in the US. The Mega Drive/Genesis on the other hand wouldn't look right in any other color. Its supposed to look like a part from an anime spaceship or a Blade Runner prop, and it does. If you changed it to white, it would just look like a bizarre variation. Gameboys generally look good in any color, and are designed that way to begin with.
Also, and this is just a historical observation, I've come to associate black systems with failed systems, and people who collected failed systems, and the failed trailers they collect them in. This probably just has more to do with my background though. If you walked into any mid-Michigan trailer house in 1993 with weed stench pouring out the windows and sounds of Mortal Kombat II...you can be sure they were playing that shit on a Genesis and not a SNES.
Also, I've known a lot of those guys who collect anything video game related as long as it sucks. They end up with a lot of systems, and they are mostly black. Sometimes you'll even see eBay auction lots like this. They'll have a Genesis with 32x, a couple of CDi and 3DOs, they will have a Saturn (with the games Gex, and Fifa 97), and a Turbo Grafx. You'll see a black Gameboy Advance in the corner of the picture at first, but then realize that its the original model and not an SP or Micro or anything you can actually see the screen on. They have a giant pile of unplayable crap. Some of it might be playable, the decent systems, but they only have the crap games.