I started kitesurfing wearing an old Gath Helmet and used it for three years. It once protected my head from a bad bump on my board in Bali - I was happy I was wearing it. Another time I had a big crash on a jump as my kite zoomed back through the power zone and I burst an ear drum on impact - wearing the helmet.
I now wear a Protec that has better impact protection.
It also keeps my head warm and my sunglasses on. I am happy to have it for some impact protection in case something unexpected goes wrong. For example, I could taken out be Jetski, and was very nearly hit by a windsurfer going at full tilt.
I figure my brain is worth $100
As an aside, helmets are not mandatory for Jetski riders in Victoria, but they do have to have a boating licence with PWC endorsement.
Most of my mates don't wear a helmet when kitesurfing. Nobody gives me any cr@p about wearing it, apart from a few posters on Seabreeze who seem to think its "uncool".
I don't think helmets should be mandatory. But
if a kitesurfing licence were to be introduced (as appears inevitable with recent accidents + deaths and irresponsible behaviour by a few + some novices who refuse to take lessons), maybe they should be mandatory for kiters for the first year while they are on "P plates".