I have no interest in mastering to 4k yet but you can't even try to pry my 4k cameras out of my hands. It just opens the doors for me as a run & gun videographer (weddings mostly) to be able to crop and recompose in post. I do this all day long with photographs...it's about freaking time I can do it for video. Plus my frame grabs when I need them are much more usable. Every now and then I even stabilize in post which usually amounts to a crop. I still have my 5D3 for photography use but almost never use it for video anymore. Canon is dead wrong if they think 4k isn't a must have. Though granted, I still have yet to master out to 4k for projects...though I do enjoy watching my home videos on my 4k tv which I do maintain at 4k. Maybe my kids will thank me someday for their high quality home videos.