Well i can tell you ripping xbox games are very easy when you upgrade your xbox with a 180gig hd....
some guys at my dorm have one and there favorite quote is:
"rent it, rip it, return it"
plus they have dvd burner with software that is VERY easy to pirate xbox games. so i believe that lucasarts might of polled the market and looked at how kotor one sold on xbox and when the sales were most so naturally they would release it around christmas for Xbox.