"I am mystified by how rapidly Sora went from launch to shutdown"

I suspect they promised synthetic movies but it quickly became clear that they were never going to be able to deliver on this.

Slick fifteen second lulz-clips, sure, but I don't think they can make several of them consistent enough to fit into a larger video narrative without the audience finding it jarring and incoherent.

Perhaps legal at Disney also concluded that the output wouldn't be possible to copyright, which is their core business.