I found Krall's reasoning a little more interesting than Nero or Khan's, especially since it is rooted in Star Trek canon. Rather than a simple act of revenge or mayhem, Edison's reasons for turning bad are more drawn out and more complicated than simply, "They have my family/ they destroyed my planet!" Edison's grievances force discussion, like what could the Federation have done differently for war veterans like him? Is Edison perhaps right? It's easy to dismiss him as yet another crazed ex-federation captain with a super weapon... but more than the other two villains so far, Edison evokes far more thought.
It isn't a stretch for me either to imagine Edison's fall. Waking up every morning to realize not only will you never see home again, but your superiors threw you away simply for defending earth, is a hardening realization. His anger was probably built for years when he finally discovered the super weapon, and honed a plan that came to fruition once the Magellan probes entered his space.
It isn't a stretch for me either to imagine Edison's fall. Waking up every morning to realize not only will you never see home again, but your superiors threw you away simply for defending earth, is a hardening realization. His anger was probably built for years when he finally discovered the super weapon, and honed a plan that came to fruition once the Magellan probes entered his space.