Separately, in a bid to shore up morale within a company that has been besieged by competition, a tough advertising market and the so far unwonted takeover gestures of Microsoft, Yahoo has introduced a campaign to encourage employees to dress in purple -- the company's primary color -- at work. source
They probably had some big managers meetings and discussioins about that and some loony imageconsultant or something of that kind came up with that.
Instead they should be working on their businessmodel. They should be looking at all those loose ends that don't match and putting forwards what they are doing right and throwing away what doesn't work.