I very much agree with you. If you're truly comfortable with yourself you don't need all that stuff to feel special, just be yourself.
Anyway, as for the topic. No, I don't think a guy who shaves his head looks weird. In fact, I've even walked around like that for a few years, it looked quite good on me. Still, my new hairstyle seems to attract more women soooo... yeah.
I don't think piercings or tattoos look good on most people though. Minor stuff could still pass, but I've seen quite a few people who push it way too far. I would never want a piercing or tattoo myself, that's for sure. I prefer the natural look. And yes, sure a girl can have earrings, but I don't react very well to all that excessive stuff.