Oh man. I work in the post industry professionally - on the documentary side, but honestly 10bit HDR (HDR10) and 12bit (Dolby Vision) are the REAL technological leaps in quality NOT 4K/UHD.
Sure resolution is nice and all, but if you have a capatible TV, we can literally force change your local settings to optimize what we want you to see (people ever notice Dolby Vision settings turn on and grey out your own settings). Being able to change your TV's color settings natively directly to what we wanted out of the box in post is by far the biggest tech advancement in post to home video in decades. UHD is 4x the pixels but HDR is up to 16 billion more colors. Trust me, it's worth the upgrade.