You can't tell the difference on a 1080p monitor, because THERE IS NO DIFFERENCE.
You're stretching more pixels onto the same amount of pixels, making it roughly the same quality.
2160p would look absolutely stunning on a 4k monitor.
and 1440p would look great on a 2k monitor.
they both look sub-par on a 1080p monitor.
Our brain processes so much information every second, and no 60fps is not the highest, I can easily tell the difference between 120fps and 80fps.
http://boallen.com/fps-compare.html
can you really not see the difference between 30 and 60? and do you truly not believe your eyes can see past 60?
And we don't have a definite number on what our eyes can see, however it IS scientifically proven that our eyes can easily see past 4k, and easily see past 60fps.
"reading up" on yahoo answers won't change anything.
If you truly can't find it yourself by googling, I'd be happy to find proof that you can see past 60fps and 4k
not just that, the entire industry is moving towards it, more higher resolution screens are being developed, and cheaper than ever before. Even movies which have always been rendered and shown in 25fps on tv and I believe up to 30fps in cinemas, are now being made in higher quality. Take for example The Hobbit, it was 48fps, and it looked absolutely fantastic, what you'd expect from a movie in this day and age.
The entire reason we are stuck in 1080p, is because that's the resolution everyone has, once 1440p becomes the norm, everything will become available in 1440p. The same goes for 2160p when that time comes.
Running games are amazing when they're above 60fps, and even if you can tell the difference when you look for it, you don't truly notice it when gaming. It's still very useful for editing, if you wanna do slowmotion without twixtor and so on. It also makes encoding for Youtube videos much smoother, even though Youtube only supports 30fps on 1080p videos atm. Youtube will soon support up towards 60fps, and it already does in 4k I believe.
On a side note this is why next gen consoles won't last many years, because they don't support 1440p natively, they only upscale games to that. Once it becomes the norm, and everyone understands it, There will be no incentive, if you want living room gaming why not get a steam box?
Very side note though, not really relevant.