Really? I've got a 50" FullHD TV and I could definitely use an upgrade to 4K. Sitting 3-4 meters away from it some content is definitely not as sharp as it could be.
What content? Netflix in 4K looks considerably worse than true BluRay at 1080p.
The resolution is really not the most important factor as most of the content most people consume now is streamed we lost pretty much all of the benefits of HD with squeezing 1080p HD content to a bitrate lower than that of DVD without much improvement with our encoders.
H265 can produce some seriously small files but atm the configuration isn't optimized yet (h264 still looks better) that plus some decent client side post processing can probably help to bring back HD content to it's full glory.
I often can't tell between 720p and 1080i source material either on my 46" 1080p set. About to buy a 75" 4k set though. The size means I'll definitely notice 4k from my couch distance (~8ft) and the sheer size will come in handy when watching TV from the kitchen table (~15ft away)