Well I sit about 6-8 feet away from my 4K TV vs about 30" for my monitor, so I am not as concerned with visuals being perfect on my TV as I would be on my PC monitor. And TVs generally have much worse input latency than a monitor, so it's a lot more noticeable if you have a slow TV. Since I use my TV primarily for gaming, that's an important consideration.
Also, the Vizio 65" M65-C1 is about 1/2 the cost of a comparable Samsung. Is the Samsung nicer? Yes. Is it worth 100% more money? No.
I concur. Adding latency to get HDMI 2.0 output is bad for gaming. AMD better wise up, and give us both DP and HDMI 2.0 next year. My large (40"+) 4K display choices are hampered by their lack of HDMI 2.0 support.