Because it doesn't affect everyone to the same degree. What you describe sounds really severe (and I don't doubt it) - but for example I'm personally way at the other end of the spectrum: I can easily spend hours in VR, and I can think of only one game that ever made me even slightly motion sick.
1. Often it’s triggered by frame rate hitches, which seems solvable with the usual advance of software and hardware over time.
2. Most folks can train their mind and body out of the motion sickness with practice.
I've given probably 30 people a try of my headset. I think two of them had problems with disorientation and nausea. The vast majority were just fine with all the stationary / teleport experiences (and there are plenty of of those). Smooth motion would be more of a problem for them but a lot can be done with 6DoF and teleporting.
It's an awkward fraction because if 10% of people can't tolerate VR at all it's definitely going to get in the way of VR becoming a ubiquitous tool where it plays an essential role in work or shared recreational experiences. But I don't think its nearly as large as people think .... many of those perceptions being formed from 5-10 years ago when headsets were vastly inferior to what they are now in terms of latency, tracking and other factors.
In other words, we can correctly assume the converse; Any application that involves the user moving in VR is presently a non-starter for the most part.
Now, how fun / interesting / useful are those S/T experiences, especially as compared to the hype of VR? I'd say a solid-but-small chunk of gaming at best. Right now, I feel like the MAX impact VR could have on the world would be roughly equivalent to the Wii's.
I'm not saying that nothing could flip the switch in the future, and I do acknowledge those "physical" careers that would benefit greatly, e.g. architecture. But I see nothing remotely close on the horizon that puts VR headsets in households on the level of iPhones or even Echos.
Our best guess is that the 6DoF system at least matches head movement, which might be the difference that makes our brain(s) not freak out compared to reading in the car, etc.