All the features you describe are the ones that major developers definitely do not want - not as in they don't care or don't understand, but they would want to

All the features you describe are the ones that major developers definitely do not want - not as in they don't care or don't understand, but they would want to ensure that they aren't possible for their content, that their content is not made available on any platforms with such features, and that any existing platforms which have their content will have legally binding promises that they won't. Owners of major franchises definitely don't want their assets to be able to be used permissionlessly, that's effectively a taboo word - they have strong interests and will (demonstrated by investments, declined deals, legal action) to ensure that they keep effective control over how their assets will be used. It's not about technical features enabling interoperability, it's about Disney saying that they will permit Vader skins that can be transferred to game B only if it is clear that this will increase total revenue i.e. if someone pays them a significant amount of money corresponding to what users might have spent on re-buying these skins if interoperability wasn't possible (and IMHO no one in the ecosystem would be willing to pay that) and under conditions that they will be able to control further interoperability to some future game C. Sure, if users 'actually owned' these skins, that wouldn't be an issue - so that's why content owners would never ever permit users to actually own these skins, not at any reasonable price, since that would permanently harm their long-term potential of extracting more money from that IP. Licensing their usage for everything from toys to other company advertisements is their core business, and they are very much aware of the value of control. They'll license it for a limited time for a limited use under terms that they'll control, that's it. And for the many platforms that thrive on user-generated content, asserting at least some control over that content (again, contrary to being permissionless and interoperable) is their key value proposition; being a privileged unavoidable intermediary is their whole business model which they would harm by adopting your proposals, so they won't.