I think any developer that implements this would be in between a rock and a hard place. On the one hand it becomes impossible to have a consistent aesthetic or theme if you liberally allow people to bring their own assets, and on the other if you allow it but somehow map resources into your aesthetic the owners will almost certainly feel ripped off.

As a player I think I would find it less than desirable to be playing Darkest Dungeon and view Halo content next to cartoon Fallguys. The NFT owner probably wants more than their NFT transformed into bytes and used as a random seed to determine the grain on their wooden shield. They almost certainly want a direct map to their resource.