So for those that do not think Canon should have put a headphone jack in this (what US$ 2000?) camera, and then (some at least) go on about external recorders, why do they bother to put a mic jack in?
You do understand that without a line/mic in you can't run a line out of an external mixer/preamp into a camera?
And you do understand how awful the headphone jack on the 5dm3 is?
Hell even having a cheap mic run straight into the camera (something like a rode ntg2 or videomic) to use as a track for something like pluraleyes to sync your high quality externally recorded sound to makes sense - and theres no reason or need to monitor that.
The 6D isn't meant to be a cinema camera - Canon did say the 5diii would be the EOS camera with better video than other offerings. But if you really wanted to use as such it would do fine - seeing as it's not pitched as a pro cameras it will no doubt be used by a lot of people for filming their kids and suchlike.
And judging video quality off a downconverted web video from a pre-production camera isn't going to tell you anything remotely definitive anyways.