I think the biggest problem is the controller and locomotion. Almost all VR games available right now use controllers to navigate around the virtual world. Meanwhile Apple has shown nothing that allows you to move around in the virtual world. All locomotion you do on Apple's headset happens in the real world via AR, the fully immersive experiences are basically limited to standing or sitting in place.
This has the advantage of dramatically increasing the comfort, since motion sickness is largely caused by artificial locomotion with the controller, but it also drastically limits what kinds of games you can do in VR.
I would expect them to expand on this area eventually, but I can understand why they wouldn't for the announcement, as for the time being they want the focus on VisionPro as a friendly computer/monitor/TV/cinema replacement.
I wonder if there is a way to stimulate the vestibular system externally to make it feel like actual locomotion and perhaps improve on the motion sickness.
I don't think so. While you can artificially stimulate the vestibular system, getting that to work precisely across all the users of the headset would be rather tricky.
But the even bigger issue is that even if you overcome that, you still have the fundamental problem that a correct vestibular response is extremely important to keep users from falling over. If you artificially give people the impression that they are accelerating or decelerating, they'll automatically compensate and lean into it and just fall over. This happens already often enough just from the visual stimulus alone, if you mess with the vestibular system those accidents would get a lot worse.
That said, maybe there is some middle ground that could work where you don't create a real virtual vestibular input, but just a little jolt to notify the brain that something is going in, even if that something isn't matching the visuals. Many people report having less issue with motion sickness when they walk in place or bob their head. PlaystationVR2 has a small rumble motor build into the headsets with is supposed to help a little bit here as well.
This has the advantage of dramatically increasing the comfort, since motion sickness is largely caused by artificial locomotion with the controller, but it also drastically limits what kinds of games you can do in VR.
I would expect them to expand on this area eventually, but I can understand why they wouldn't for the announcement, as for the time being they want the focus on VisionPro as a friendly computer/monitor/TV/cinema replacement.