As I understand it GRBs are highly directional because the magnetic fields involved in the explosion for us energy into narrow beams. We see the events as GRBs

As I understand it GRBs are highly directional because the magnetic fields involved in the explosion for us energy into narrow beams. We see the events as GRBs when we cross through the path of the beam. When we see the same type of supernova from the side we still see a bright burst but not nearly as bright as as GRB. If a supernova goes off in your stellar neighborhood you might be screwed if you're in the beam of the GRB or just mildly inconvenienced (minor mass extinction) if you get a side view. So the events causing GRBs are slightly less horrifying than galaxy-sterilizing monsters.