There is no benefit, unless you sit way closer than normal to the TV. At a normal 10' viewing distance, you can't distinguish individual pixels on a 1080p screen unless it's like 65" or more. Which means you will benefit very little (or not at all) from a higher resolution.
Because "bigger means better"
TBH HDR is a much bigger deal than 4K. Also, on consoles 4K does matter more, as the more powerful Xbox One X and PS4 Pro are able to run games with higher graphics detail (although you don't actually need to be playing in 4K to benefit from that)
You will get the point once you get one. I was blown away with my PS4 Pro and with some 4K movies on the 4K tv. The details are absolutely stunning, not to mention HDR makes everything even better.
My friend has a 4K TV, my opinion stands for now. There aren't enough things that make use of 4K. Heck, in my country most tv channels aren't in HD yet, there are only two or so 4K channels, and they're boring channels at that.
As for movies, I haven't seen many 4K movies available either. ATM I don't see the point in getting one. Not enough benefits.
they need to have a strong line up on the launch titles too. I think they should move metroid prime 4 to the next console because by now it has been quite a while and there's no release date scheduled yet