I’ve never ridden a motorcycle, but I have had a bug (and part of its web) go into my mouth and down my throat while biking. Just thinking about it makes me want to gag. If, after that, you offered me a bike helmet with a front visor, I’d have put that thing on ASAP.

Now take that bug incident and make it happen at 30-50 mph? No way would I have my face hole exposed for bugs to invade! (And that’s totally apart from the safety issue.)