To paraphrase Bill Gates (who never actually said the original, but anyway) 4K should be enough for everybody. Having seen 1080p stretch and play nicely on a 30 feet cinema screen, and not being much worse looking from regular Hollywood titles even for front seat viewing, I don't see the allure of 8K even for "future-proofing". Sure, monitors and tvs might improve their resolution in the future. But I don't se human…
For traditional 2D screens, I tend to agree with you - that 4K is quite enough. But for Virtual Reality, these higher definitions are a must. 8K per eye will be much better than 4K per eye - at least that's the thought at the moment.
Sure the increase in resolution is "imperceptible" in terms of individual elements building up a particular frame, but to assume a visual cortex can't discern increased detail is just arrogant and borderline laughable