I think the plug/jack has serious physical weaknesses and when the cable is stiff enough, it guarantees breakage at the end of the cable or the jack, Or, it just pushes lightweight equipment out of the cabinet. I think a single cable system is great, if it's designed properly. Why this couldn't be a round connector, I don't know- it could screw in or a clip-style retainer could be used that's similar to the kind on some power cords. Since nobody used the HDMI retainers, the AVR manufacturers stopped using the screws for this and started to use them for mounting the board.

If all HDMI cables could be flexible and harder to remove, I doubt we wold see as many problems.