It's not stupid, it's your choice (unless you under 16).
The pros outweigh the cons for me, which is why I wear a helmet 90% of the time.
The cons I hear are usually helmet hair, inconveniance, style (especially the middle schoolers I work with), what to do with hair (especially afros, bunches of dreads, and people with 'big' hair), one more thing to lose/lock/carry, a false sense of security (some say they ride more thoughtfully when they don't wear one), and then idealstic reasons. One study showed motorists pass closer to helmeted cyclists.
Helmets are a good piece of safety equipment but it's the last piece of the four tiers of safety-
Don't cause crashes (ride legally, safe & smart).
Deter crashes with road positioning.
Escape crashes by riding defensively.
THEN
Survive crashes with safety equipment.
The majority of crashes would be prevented by doing the first three... Like this one in Salem.
Shane