There were a lot of Sega titles near launch of the system on the original XBox.
Panzer Dragoon Orta
Shenmue 2 US release
Crazy Taxi 3
Jet Set Radio Grind Future
and a few others if I can remember
I wouldn't be suprised to see someone buy a XBox when it was first released just because it had so many sequels of games from the Dreamcast system.
It's just that simple.