Good point. It's all about balance though. People have been riding on boats on water for a long long time (most of it without the invention of sunglasses). And similar to the truck drivers who drive hours with one side exposed, or people who sunbathe a bunch - that is unbalanced. Staring at the sun at full brightness would be unbalanced. But I think never looking at it is also unbalanced. You can look at it, but keep your eyes moving - don't focus and stare at it for seconds (unless it's really low on the horizon, and then I think it is okay to stare at the sun).