+2
It may not be so much whether the eye can perceive a resolution as it is the size of your television and the space requirement that the resolution can fill.
For example, say you have a 65" screen. The image quality of a video at 480x720 would look horrible at that size so a higher resolution video would be preferable to avoid pixelation and to improve over all viewing quality. The more resolution the source provides, the more image detail there is to spread across the larger display---generally speaking.
That's not to say 4k is a requirement. HD I'm sure is quality enough. Times you might notice differences would include when text is displayed. Take for instance the scene in Fight Club where Norton's character is ordering a dinette set. The camera is panning through his apartment as small sales descriptions pop up over the various products that he has purchased for his apartment. Even on my DVD copy you can't read them. Its possible, though, that a bluray or 4k resolution copy might be readable as there would be more resolution to show such details. Of course that depends on how the higher resolution is processed. Just upscaling the lower resolution source wouldn't help.
All of this is moot if your television doesn't support 4k.