A good VR experience (and preventing motion sickness) requires fast response time. This requires low latency of the entire chain from the motion sensing device, through the USB connection, OS process scheduling, scene calculation and rendering and any buffering in the video card and display.
A system that is able to respond quickly can obviously produce more frames per second. But just creating more frames per second without reducing latency will not help the experience feel more convincing (or prevent you from feeling queezy). It will just look a bit smoother.
In playback of canned video latency does not matter much. In fact, generating these in-between images actually increases overall latency as the system has to delay the next image while calculating and displaying the in-between image. As long as an equivalent delay is inserted into the audio nobody notices this. But it won't work for VR.
There is, however, a method to produce faster response without calculating more images per second. The most critical movements are those of the head and the change in the scene from such motions can be approximated by simple panning. It's not perfect, but does work to reduce motion sickness.