I think you would be surprised how many sailors wear hats these days. Most of the guys I sail with wear them and sunnies are becoming more and more popular.
Ive already had pterygiums cut off both eyes and skin cancers cut off and zapped.
I also guess it might have something to do with how much hair you have

Most of the big surf wear companies make version these days, well worth it.
I mean, if Mr Lockwood wears one they must be fast