IP is not worth a damn, if you arent making it.I am not following your point. They had a lot of IP?
They weren't an Activison or Bethesda. Sorry. Compare their IP to big hitters of their day. Not exactly the same as CoD or Skyrim. They were really small IP.
These games on other hand, were from different studios. Psygnosis was their publisher. That is much a bigger issue than just owning activision. It meant that all these games had to come to playstation console, if psygnosis wants to publish them, giving other developers no option but to accept it.