I know they say to fold them but I never do. Never did in my last Toyota either. Never had an issue, brushesmoed right past them and helpedcen the mirror glass as well (when it wasn't a touch less anyway).
Happy that I don't have to unscrew the antenna mast though as I had to do in the prior vehicle!
I use a touchless wash but having the mirror fold in allows for better pressure on the front of the mirror to clean off the bugs. While this is a first world problem, I am watching this thread!