Graphics hardware architectures continue to evolve toward a performance that benefits rendering pipelines for virtual reality and 3D graphics. VR introduced requirements that weren't very important for traditional video gaming just a few years ago. Latency and dropped frames (where rendering a frame takes longer than the refresh rate) took a back seat to high-fidelity AAA rendering capabilities. VR needs to render each frame in time and do it twice: once for each eye. Driven by the requirements of this emerging industry, semiconductor and hardware manufacturers are building new and improved devices, which will inevitably impact how content developers think about optimization.
That said, you should develop and optimize for the lower specs that you want to target. If such optimizations necessitate undesirable compromises, consider separate versions of the game for high- versus low-end platforms. VR device manufacturers have started...