Hell just try reading small text, it has to be way bigger on the 1080 before your eyes are straining to read it.
12pt font is 16 pixels tall on 640x480, 800x600, 1280x720, 1920x1080, and 3840 x 2160. On 1080p, 12pt text is 1/68th the height of the screen. On 4k, the text is 1/135th the height. The improved perception of quality is all in your head.
This happened to the Monster cable customers too. In a way, the situation is worse because the text is getting smaller and smaller and more unreadable but customers believe there are more pixels packed in somewhere and it’s actually making it easier to read.