I never use it either, but it could be handy for adding the sketch geometry as an after thought. If you decide after the line is creataed that you need an offset you would need to create the three lines and then use the trim tool to get rid of the segment you didnt want or just use the jog tool instead.
I used it back in the "good ole' days" of 2D CAD. Never anymore.
I would use the jog tool if I used sheet metal more.
I do use the jog for extension lines on dimensions.
I've never used the Jog Line tool in a regular sketch and probably never will. I find it quicker to use a Corner Rectangle (which adds dimensions) and a Trim.
Like any other tool in SWs arsenal, the Jog Line is there to be used, or misused, as people see fit.