> the human eye has difficulty seeing more than 60hz.
Not true. And, a broad claim like that conflates many different concepts. Flicker fusion can require 85 Hz to not cause headaches for some people (especially with the low persistence needed for non-blurry VR), and smooth motion continues to feel smoother up to at least 120 Hz.
In addition, lower frame rates generally mean increased latency, and latency is probably the biggest cause of VR nausea.
But don't take my word for it. This blog post does a great job of summarizing the latest research on the topic:
I have no idea what cheap CPUs and server I/O have to do with motion tracking, but tracking a single point (translation and rotation) is exactly what is needed for VR -- that point is the user's head, and tracking it with low latency is what makes VR work.
> The only difference between now and 20 years ago...
is everything. The technology is orders of magnitude cheaper and more capable.