What is the primary function of motorcycle riding gloves made of abrasion-resistant leather with palm reinforcement?

1. To protect hands from road rash and bone fractures during a fall, prevent blisters, and maintain a firm grip on throttle and brake levers
2. To improve the rider's grip strength so the handlebars need less effort to turn
3. To insulate the rider from vibration transmitted through the handlebars
4. To keep the hands warm, which is their only practical function