4k TV's are just a gimmick, they use them to prove how good they are if consumers sit close to them. The demos are literally "stand 1 foot away from the display and you won't be able to see pixels". Absolutely ridiculous, the only reason I personally am excited about is Passive 4k TV's due to 1920x1080 for each eye, I believe this is worth talking about. But noo, I bet you they already have demos of their 8k+ TV sets with a live demo for people to stand as close so their nose pokes the screen, and you can't see pixels, whoa!
Oh, in a monitor. That makes even less sense. From a normal seating distance which is typically 3-4 feet, there can be some benefit, but really. The amount of resources required to drive these displays at settings that make the games look stunning, is just not worth it- yet. If for whatever reason you move away from your high resolution monitor, you wouldn't be able to read the text on it unless you wear binoculars.