What an inane reason, you may say.
But IMHO it was one of the best features ever introduced into desktop computing. Simple, easy to see colored backgrounds that you could assign to files to organize or tag them as you saw fit. (seen/not seen, reviewed/not reviewed, good/bad/meh, and so on)
Maybe Mac users are less vocal about the removal of features (or they are simply fewer) but this kind of blatant disregard for the needs and established workflows of your customers has a long term effect on a company's image.