When 4K TVs came out, some people complained that you can't see that level of detail...
Much depends upon how big your screen is, how far you sit from it, and whether you are John Coffey. My eyesight has never been 20/20, but even with the corrective lens I got during my cataract surgery, which was a huge improvement, I see more like 20/25. So when 4K first came out, I had a hard time telling the difference between 4K (which is just a marketing name for 2160p) and 1080p.
Although surgery vastly improved my distance vision, it made it harder for me to see up close. I can't see anything up close without reading glasses, and getting the right focus for playing chess has been tricky. I liked my old vision because I needed glasses just for distance, but now I need strong reading glasses to see my phone.
For a large-screen TV, a 4K display makes sense. However, I have two 27-inch monitors, and for these, I feel that 1440p is ideal. On a 27-inch monitor, 1080p is not as good because you can see individual pixels when sitting close, but 4K makes all the Windows and Mac icons look small, so you have to artificially enlarge them to be able to see anything comfortably.
I don't think that a person is going to gain anything by having 4K on a 27-inch monitor. There is a limit to what our eyes can see. Although it doesn't make much difference, 4K requires more overhead from the graphics hardware when playing games, so you can get a better frame rate with 1440p. Although you could run a game in 1440p on a 4K monitor, it is less than ideal because the video output doesn't match the pixels on the screen, requiring the computer or monitor to scale the images.
My iMac is 5K, but I run it at half resolution, which is 1440p, and I am more comfortable with it that way. For people who do video or photo editing, 4K and 5K are better.
On a smaller computer monitor, such as one measuring 19 or 20 inches, I think that 1080p might be fine. Most laptops have displays with resolutions higher than 1080p, but because of their size, I don't think that they need to.
Because of the small screen and keyboard, I don't recommend using a laptop as your main computer, but I have used a laptop with an external screen and keyboard.
