Your appearance and what you wear has not thing to do with how "serious" you are.
Calling out the other guys over what they wear is always a minefield in my books; it just makes you look a bit too queer eye for the airsoft guy.
The main advantage of a helmet is that it will stop BBs. Trust me anywhere you have a thin layer of skin over bone is not a good place to be shot.
Wearing camo? Maybe a good idea in the woods unless you like being the first guy shot all the time. Wearing a vest etc. great way to carry water and magazines and the rest. Helmets, boots, and gloves, all great ways to make sure you don't get a bleeder in the scalp, twist an ankle or fill your hand with thorns.
Stuff like fake GPS or CAT tourniquets is a bit much but I've never seen anyone around here with one so I"m not worried that I'll see one and go all over to the other side.
Airsoft, where nothing is hurt but feelings.