By definition, motorcycling involves wearing a helmet. It protects you, but it also shields you from the outside world.
Some people enjoy the feeling of being alone in the world, others find it antisocial or lonely. Besides, you can't always wait until you're sitting on a terrace to exchange a word with your pillion rider or fellow traveller.
Motorcycling is of course far from lonely, even if you're on your own, but in modern times there are plenty of modern communication possibilities that keep you in touch with the world outside your helmet.