I'm also worried about the actual effects of motion sickness once it becomes actually mass consumer affordable. Generally, reports are that VR can be particularly rough for most folks.
As I understand it, the motion sickness is directly related to rendering lag. Outside of VR there isn't much of an incentive to reduce that lag - as the only people who really care much about it now are the most enthusiastic of PC gamers. There is a lot of buffering and synchronization between the software and our retinas right now, so the hardware advancement needed to enable motion sick free VR (low lag GPU and display) is going to have to come from a drive to specifically deliver motion sick free VR.
We already have virtually zero latency in VR at the moment thanks to predictive tracking and rewarping of the frames to the predicted head pose and direct driver support.
The motion sickness is mostly coming from vection now, when you move in VR but not in real reality. It's an active area of research, people are experimenting with things like reducing the FOV while moving, using interactive overlaid grid to pull the scene around, etc.
No, it's not just due to rendering lag. Motion sickness is caused by a disparity between the what the eyes perceive as motion and the vestibular system of the inner ear [0].
That's not all, though. Another major problem with VR is the lack of compensation for vergence [1] and accommodation [2]. These two systems are critical for depth perception and when they are not accounted for the result is confusion of the visual system, eye strain, fatigue, and even nausea.
While I enjoyed the DK2, I got unbearably sick from Half-Life 2 within a half hour. Playing with Tilt Brush on the Vive, I didn't feel the slightest bit queasy.
Not sure if the difference was the hardware or the software, but it seems like a solvable problem.
FPS games are inherently a million times worse for VR sickness than room-scale walking around, since the former has the mismatch of the avatar walking around with the player sitting in a chair, while the latter is 1:1
HL2 is the only game that I felt nauseous from. Wonder why? I stopped playing though instead of trying finding a solution so I don't know if it's a known problem.
I am pretty sensitive to motion sickness ... get sick easily in cars, awful in boats and have suffered week-long bouts of pretty nasty positional vertigo a few times in my life but I can stay in the Vive for hours with no ill effects at all. It doesn't feel like my vestibular system is under any sort of stress at all, the tracking is super tight. My assumption is that the majority of people that experience nausea do so due to either defective hardware, or under-powered systems.
I think it's the games. Room scale games, like Fantastic Contraption, induced no motion sickness on the twenty or so people I had trying it out. Games where your avatar is moving but you physically aren't are dangerous territory. I never tried HL2, but I easily imagine it begin nauseating.
There is a reason why most current demos or games do not give you full control of movement, and the demos that give you mouse / keyboard controls to move around a space with jerky accelerated motion do cause problems. I think we'll get better in time with control schemes and design that does not cause nausea.
I own a Vive. Zero motion sickness on room scale games, zero when flying around in Elite:Dangerous. However, get me in something with wheels and it's hell. Rolling in the buggy in Elite is bad, driving in Project Cars is worse.
I've learned that, in Elite, if I look at where the buggy is going (it power slides a lot), then I almost avoid motion sickness. Project Cars, though, I can't play. Cornering, at high speed, completely immersed, with no lateral acceleration, triggers some alarm in me.
VR or no VR, I always play car games from the perspective of the driver's seat or, in some cases, from the front bumper cam. Playing from the third person perspective cam is a bit too arcade for me.
So, my description above is for playing from the driver's seat perspective.
I don't know if it is overblown, but it is certainly real. I've only experience motion sickness under two conditions: helicopter flight on moonless nights, and developing software for the original rift. It was a real bummer, after a few uncomfortable weeks I put it back in the case and haven't touched it since.