And then some - hadn't really thought about it until your comment, but somehow we regressed from infinite orientations (well, in that plane) to one, and are now all excited about having two...

Are there any example of barrel-style connectors with >2 pins, i.e. coaxial barrels? Similar is the 'jack' (3.5mm and such) but with split regions along a single pin rather than concentric rings of course. I wonder why such designs aren't more popular/explored (that I'm aware of anyway) for multi-pin data connections?