Correct me if I'm wrong, but all the decoding and positional stuff on these 3d audio solutions are done on device and then sent to the speakers.
It's more about locked down copy protection and licensed decoders than anything. After all, Sonys pushing 3D audio from a 3.5mm jack in the controller to ear buds.
For a headset, you just need need a device that can decode Atmos/DTSX/Sonys format and send a stereo signal to a headset.
Incorrect.
Digital Audio formats like 7.1 or 3D audio are high bandwidth. They send a lot of digital information over to the receiver, and they need to do it at a certain speed.
An optical port is a digital out, but can't carry enough information to support a 7.1 or 3D audio signal going to the receiver.
Its not a "licensed decoder" issue, the cable simply can't carry the signal. It's like asking why you can't get a 1080p signal to your TV using composite or S-video.
As for getting audio via the controller's connection that's using Bluetooth not a "stereo jack" to pick up the signal from the Ps4. I don't know a ton about Bluetooth audio but I'm pretty sure it's highly compressed and severely limited compared to what would be coming from a wired HDMI connection to a receiver.
AFAIK the Sony Platinum headsets that support 7.1 and 3D audio don't use Bluetooth because of this. They have a separate wireless dongle using some other standard. Don't know what that is though, don't own those and don't plan to.