To me it seems the big thing 4k improves on is video immersiveness. After all, reality is 210 degrees field of view, not a comparatively tiny rectangle metres away, and it's crisp and sharp, not somewhat blurry-ish like Full HD at somewhat closer range. I like being able to have a considerably bigger rectangle in my face while still getting acceptable quality; 4k at 60fps is a joy, feels real in a way movies usually don't. Besides, on mobile devices and tablets especially, it's really neat to be able to pinch-zoom into a video and still get some quality. That's not possible with Full HD.

As for Chromium (and by extension all major modern browsers), it's played a pretty important part in making the web a platform to reach pretty much everyone with comparably little effort. A lot of the productivity applications I use day-to-day are web apps, and I guess most wouldn't exist in their anything like their current form if there had to be native Windows, Mac, iOS, and Android apps that people would have to download and install and update and secure (and certainly no Linux app – way too few users to even think about).

To my mind that adds a lot of intrinsic value, at the price of much higher resource consumption, true, but I'd rather have that than the snail pace of innovation and still usually questionable quality we had in the "old days"...