Because it's missing (interesting) content maybe?
Content is a bandwidth issue. If you need so much bandwidth for a flat, planar 4k stream, how many more do you need for a 100 planes (still pretty flat IMHO) for depth ? Or 1000 planes ?
Maybe it can explode with Gaussian Splats, since it's a convenient way to save a volumetric scene, but, until now, no one made a Gaussian Splats video, so I wonder the bandwidth and processing power required for these too.
good point it's like the ongoing VR problem in that there's just no killer content that would convince you to buy one.
btw there is some video work being done on Gaussian splats: https://shape-of-motion.github.io/