Because by then it was old. I'm not saying that was a good reason, I'm just saying that was the reason.
Bad timing has screwed us out of a lot of good games. I *really* wanted a home version of Scud Race/Super GT, but the Saturn couldn't pull it off, and by the time the DC came out the game was old news. I still play this game in arcades regularly to this day. Its my absolute favorite arcade racer.