The problem is that VR performance is tightly coupled to GPU performance. Currently, adding more pixels requires an equivalent increase in GPU performance to maintain quality.
I'm prepared to believe that e.g. foveal rendering will give step-wise improvements without more GPU power, but it's not the same as the years of continual process improvements were for GPUs.
The VR adoption got slowed down quite signifanctly by the artficial price inflation through the cryptomining boom happening in the same period over the last 3-4 years. Before that high-mid to high end GPUs were in a range of USD 200 to 500, inbetween they tripled in price and are now slowly going back. When FOVeated rendering and the equivalent of 2x4k at 90FPS+ are doable significantly below USD 500, i'm sure things will look different quite soon again.
Before that, you could double GPU performance for same price every two years or so, now its about 5 or more years, when looking at GTX 970 vs RTX 2070 for example. In my opinion GPUs speed are at least three years behind trajectory because of this market anomaly. Just hope AI isn't throwing stupid money at GPUs again.
I'm prepared to believe that e.g. foveal rendering will give step-wise improvements without more GPU power, but it's not the same as the years of continual process improvements were for GPUs.