I'm a video producer, I shoot 4K for commercials and news gathering, even though I'm posting to 1080 the majority of the time. 4K source footage looks a lot better when displayed on a 1080 format than 1080 source footage. It also gives me the easy flexibility to cut in and out, instead of having to reshoot the interview with different angles, or carry multiple cameras. Shooting in 4K also allows me to use the footage for a few more years. I love the DSLR form factor because I can keep a low profile during major news events, plus, the size gives me the flexibility to be a lot more mobile.
I wish Canon would take note from Sony, making it possible to add XLR through an adapter on a hot shoe would make the cameras a lot more usable. Some people complain about MJPEG, but the MJPEG is fine. The reason it is used is because it doesn't require as much encoding power, and it keeps the heat down in the camera. Plus, the MJPEG plays back a lot easier on older computers than H.265.
I understand that Canon doesn't want to cannibalize their sales by offering 4K in their smaller options. But they're only forcing me to ride out my older 5D Mark III for a longer period of time as a stills camera, I've bought into Panasonic to hold me over until Canon can get their act together. The GH5 with internal 10 bit 4K will be my next run and gun shooter if Canon doesn't step up.