It is absurd to condemn them because they do not often display any deep or sensitive charaterization. They oughtn't to. It is a fault if they do. Wells's Cavor and Bedford have rather too much than too little character. Every good writer knows that hte more unusual the scenes and events of his story are, the slighter, the more ordinary, the more typical his persons should be....To tell how odd things struck odd people is to have an oddity too much: he who is to see strange sights must not himself be strange. He ought to be as nearly as possible Everyman or Anyman. Of course, we must not confuse slight or typical characterisation with impossible or unconvincing characterisation. Falsification of character will always spoil a story. But character can apparently be reduced, simplified, to almost any extent with wholly satisfactory results.
C. S. Lewis, "On Science Fiction," On Stories, HarperOne (San Francisco: 2017) p.90.