Studios are essentially big piles of cash to fund movies; rights to scripts, stories and IPs to make movies; and contracts to distribute movies (and, since everything old is new again, they now also own streaming services rather than movie theaters). So it makes economic sense to lock down as much IP as possible that can then be used to generate an endless torrent of remakes, sequels, adaptations, secondary media, adaptations of secondary media, remakes of adaptations of secondary media, and so on; much more cost-effective than hunting for new screenplays in the slush pile, and much more comforting to the investors to see the next two years of movies on a PowerPoint slide at the shareholder meeting, even if you have no idea what those movies are beyond a title and some executive producer's vague plan.