Well, that's a totally extreme example. I'd choose 4K at 30 fps over 420/100+fps anyday. However, I'd choose 1440p/60 over 4K/30. 4K matters, it makes the image amazingly clear. Going back to 1080p looks like a mess of aliasing and shimmering artifacts.

Of course, there's diminishing returns beyond 4K. That's 12 MP, and that's good enough for most TV and PC viewing from regular viewing distances. So I hope for the next gen the focus is on 4K/60 instead of 8K/30.