The angled connectors can add security in certain situations, especially where straight plugs will take to much space to be mounted in a secure way so that it won’t unplug if some pulls the chord.
I use them on powersupplies like DC10 and the ones from Harley Benton that allows forwarding of 220-240V to other devices like as in my case solid state power amps.
The power supplies are mounted in racks with the connection comming sideways so that it can’t be unplugged by accident, cheaper solution than mounting speakon power connectors.