Supervillains and unusual weapons

Why do supervillains spend so much time and effort developing hand-held freeze rays, death rays and other weapons when we already have ordinary guns? Either they have some kind of fixation with non-lethal weapons or they want to prove their intelligence by going out of their way to create unusual ways of doing harm and incapacitating people.

Mokalus of Borg

PS - Personally, I'd probably go with a freeze ray.
PPS - Not an ice ray, but more of a time-stopping gun.