When one or more Walls are selected the OPTION-BAR is shown. Please insert there a Check-Box (or two for each End of the Wall) to Disable Wall-Joining. Right-clicking doesn't work very good and only for a single Wall-End
Usually, when I right click on that blue dot, it selects a different wall and gives me the wrong right click menu. Instead, I always isolate the wall first, then do it. to make the process faster, I have assigned a shortcut to isolate function.
you still have to do both ends, but isolating helps a whole lot.
You also can use the wall join tool to disallow the joins.
Thanks for taking the time to submit your idea. Unfortunately, this idea did not get the support of the community over the last 6 months and as such we will not be pursuing it at this time. Please feel free to rework (titles and clear descriptions are really important) and resubmit this one down the road.