Purple is not bad at all it was one of Sun's recognition mark for years, say what, decades!
When they initially started with brown, people associated it with dirt, mud and uh some "completey different" things that need not be elaborated upon here. No doubt they want to get away from these associations. Orange would have worked, but their theme ended up being brown, not orange. (Amateur designer's hint: don't have any pixel with a lightness below 128/255 for Orange.)