Well, originally I was going to ask why Sega doesn't own the rights to Shenmue anymore, but after a quick Google search I found out that Sega just didn't bother doing anything with it and lost the trademark.
** Please note: I understand Sega still owns the rights to some of these franchises in Japan and possibly other markets, but I'm strictly referring to the United States where the copyright laws are different. Remember, Sega can own the rights to something in Japan, but not hold the rights to the exact same thing at the exact same time in the US.
I've noticed some screwy releases for the Shining series as well, which, over the last decade, has been published by Infrogrames (now a defunct company), Atlus, and Sega. I'm sure that was just an issue involving regional publishing, but that doesn't explain the disappearance of other Sega IP's they haven't used in a while, like Phantasy Star, Vectorman, or Altered Beasts.
I guess Alex Kidd has appeared in a couple of Sega's racing games, but then again Ryo Hazuki was a DLC character for the PC version of Sonic & All-Stars Racing Transforms, even though they lost the Shenmue rights.
Yeah, copyright laws are confusing. I doubt it, but can anyone drop some knowledge on me and clear this all up?