Cars going 70 through there slamming on brakes for the stop lights are a real issue.
True...but you know the light is there and “should” be ready for it...most have advance flashing light warnings ahead of the intersection. At least its that way on roads I travel.
The J intersection is much more random and uncertain with regard to speed of the merging traffic, yeilding, the judgment of the turning driver with regard to distance etc. IMHO, a turning tractor trailer rig trying to get back up to speed would be a huge concern to me especially in more adverse conditions like snow, rain or fog.