I've been flying jet transports for a long while, and whenever I pull out a checklist, I think of the advice given to me as a young FO, and that was.....everything we do up here is because somebody screwed up. That's why we use checklists.
It doesn't matter how simple the aircraft is, use checklists, and then it isn't forgotten; well mostly it isn't forgotten, but doesn't that tell you something? If we can still screw up with a checklist, then what would itbe like without one?
Checkists are like uniforms. They're a form of discipline; simple as that.