I think a lot of people don't wear helmets particularly because they look (and feel) a little weird. Honestly, I only use mine when I'm riding park or backcountry and I know I'm going to be seriously pushing my abilities or possibly being inverted.
And the day it's going to be an "easy" day is the day you're going to have your brains spilled out. Take it from me, I know.
If you have a helmet why not wear it all the time? Because you feel dorky? You'll look a lot more goofy when your mom is feeding you baby food.
Not trying to start shit. I was the idiot who didn't wear mine because it didn't look cool. And the day I was taking it easy is the day I wrecked myself. Just hoping people learn from me so they don't experience the shit I had to live through.