The IPs were created in a specific environment, with a specific set of people coming together to make them. Sure, others can join and create things of the same quality if the same environment is still present. But after so many years the minds these the IPs spawned from have almost all long since moved on or fill other roles. So if the current owners of the IP have no respect for it, dont care, etc. There’s zero reason to still remain invested after its shown they cant live up to the quality and promise of the original creators.