Cross gen comparisons is probably not a great example, given old hardware is holding back games. A better comparisons is Rachet remake vs Rift. There is a very significant difference. The difference is there, but just is expensive. Alan Wake and Cyberpunk are additional good examples. This gen was held back with cross gen ports which is giving (imho) a false view of diminishing returns.
If people care is an entirely different discussion. I would guess most don't because ps4 games still look great, unlike ps1 games. And performance isn't cheap.