> You want to store assets in JSON? Why?

Why not have both options? .gltf and .glb being possible for assets been more than helpful to me more than once, having the option gives you the best of both worlds :)

What's Apple's incentive for having two different asset pack formats? It seems like more work to support parsing and generating both, and Apple expects you to use their tools to generate asset packs.

Working with binary files really isn't that hard. If Apple documented the .car format, writing your own parser wouldn't be difficult. It's not like it's a complicated format. Still, Apple clearly doesn't intend for people to make their own .car generators; to them, ease of reverse engineering is a bug, not a feature.