"Why exactly are data recorders antiquated? I mean the concept, not a specific device."
They aren't, in the slightest.
"Pilots hate this idea because it will show they are human."
Exactly that. You, of course, already know it. You want non-instrumental data recorders because not everything that happens in a flight is measured by instruments. You already have voice recordings and, as you say, they are triggered in specific moments and events. Video could be the same as long as it offers more relevant information than other techniques -and it sure can do, or else we wouldn't have developed TV, radio being enough.
"They make jokes, complain about work, talk about their weekends, etc."
Exactly. They *already* do this despite having their conversations saved so, what's the added problem about video imaginery?
If it can be used to increase flight safety it must be put in place. Full stop.
It's only that it have to cope with the fact that part of the "machinery" is human and it has, therefore, to cope with "human envelope conditions" which include there must be moments for relax and moments for intimacy, just like is already happening with the currently in place data logging facilities.