The original was developed just for Xbox, remember?
At X06, Ubisoft made an interesting move by announcing the next Splinter Cell sequel -- the one to come after Double Agent, which isn't even released yet -- would be exclusive to Xbox 360. Obviously, there was some backdoor negotiations going on to secure this exclusive (what was Ubisoft promised?), but GamesIndustry.biz talked with company president Yves Guillemot for an explanation.
"Splinter Cell was created on the first Xbox, so we thought it was important to come back for one volume with Microsoft to create a very good quality title focused on using the full power of the system," he said.