Windshield or windscreen purpose??????

[Hypno Rider]

What's up guys? I've done a search and still can't find what im looking for on this topic. What is the real purpose of the windshield? How useful is it anyway? Or is it annoying? I understand, overstand and innerstand that 1. It shields you from wind. 2. It can protect you from a rock flying off a big Riggs tire and 3. Protects you from a June bug at 60 mph. However, for a few weeks I rode a 250cc Honda reflex with the big windshield and I just thought it was so annoying. I've also read that wind noise is much louder in the helmet with a windshield. I guess I'm trying to figure out if I should go that route or not. I personally don't like the "look" of bikes with windshields but my safety is always first. P.S. does it slow you down at all?