I don't care what others say or don't say, or wear or don't wear. As bhop mentioned, I came to the same conclusion on my own. As I was riding, I noticed the upper part of my visual field was obscured by the visor. So, all the visors come off of my helmets. I'd rather have something for shade or as mentioned, protecting the eyes from the evening sun. But, choose to have the most unobstructed forward view possible.

I presume bikes with a more upright riding position would be less affected by the issue.