I tell people I'm fishing with in my boat that they must wear eye protection. PFDs are optional, but eye protection is a must. I have 2 pairs of $20 glasses for them to choose from, and 4 nicer pairs for myself. Some have very little tint, so I can wear them in low light and still be protected. I even have a very light pair of clear shop glasses for night fishing because the last thing in the world I want is to catch a Jitterbug in the face that I didn't see coming.
I had my lip split wide open by a flying crankbait a few years back. Had that hit me in the eye, even a closed eye, I'd be hurtin...bad.
Not to mention, they'll help you see cover and catch fish. Also, if you ever get into wading, you'll be able to see where you're stepping and that will keep you from falling.