Could be released from the other end of the connector, i.e the panel mount being the female, and the male barb having retractable locking pins at the tip or something.
Ive never seen then but like yourself have looked a fair few times. Could well be a gap in the market!
If you ever find something please post as I would love to build something like that into some workbenches so that it doesn't stick out. A neighbor of mine recessed his connects into the wall using some flush mount hinged door telephone boxes (his son works for AT&T.) The step up is nice as its clean looking and out of the way when not in use. However, it would be great if there was a smaller of more compact version of a quick disconnect coupler as it would open up quite a few possibilities.