Actually, most PC manufacturers have their own Windows image, with the same bloatware that you can find on some phones. Some of it is really customized settings interface (very common for WiFi configuration for example) which I supposed might be necessary sometimes, but otherwise you still find a lot of unnecessary trials and horrible background images.
There was a period where they did. Where one of the reasons people buy a certain brand of PC (like Packard-Bell) was that it came with a unique UI experience.
But then that got to be seen as a negative, the market reacted, and those custom skins disappeared. I don't want Sony's Rachael interface so I don't buy an X10, and if enough people feel that way Sony will either improve it or dump it. That's how a normal market works.
