It's similar for me for 1080p. When I have my laptop connected to the living room TV (37"), there is no way I read small text from the sofa, which is aprox. 3 metres (~10ft) from the TV. I had to walk up to the TV everytime I wanted to read a file name. It's not just me as no one else here could read small print on the TV from the sofa.
So for anyone considering 4K, first try connecting a laptop to the current Full HD set, setting the output to 1920x1080 and reading the date/time at the bottom right of the screen from the sofa. If it can't be read or is barely readable, then it's pointless going 4K, at least not without going for a far bigger TV.