it's funny to hear people talk smack about something they don't know anything about....
mtn. biking can be easy and relaxing or it can be a calorie burning experience.
bmx riding (stunt riding) can be an easy and somewhat relaxing or it can be a calorie burning experience.

????That BMX helmet arrived today and it's perfect. But do I really need the chin strap????

I think only you can make that decision. if the helmet fits without it, is snug on your head then maybe not. if you don't go around bashing your head onto the ground then probably not.

I've seen guys helmets fly off on a bad crash before they even hit the ground.

In frosty weather like this, I do wipe out ... about 1X year. Hit my head several times on pavement and my helmets worok hard. Helmet fits suggly ... but maybe the strap is a good idea.