And why spell it "color" like the Romans did when you can blithely attempt to imitate the French aristocracy by injecting arbitrary "u"s into random words, thus giving you license to complain about CSS keywords for the rest of recorded history? :P
The Norman conquest of England brought with it pork, beef, mutton and plenty of other adaptations of Old French words. The nobility ingratiated themselves by adopting the new vocabulary, and doing so (true for most of history, I imagine) stood out as a social status signal. The way of speaking filtered down to the lower classes over time.