Accidents do happen! When tackling rough terrain and encountering numerous obstacles the odds are not in your favour.
Although armour can restrict movement somewhat, there are times when this is preferable to serious injury.
Body armour can come in different styles for different places on the body, protecting your arms or legs. Some armour can be lighter in weight, increasing manoeuvrability with the expense of protection. You will even get some armour that can be soft, but will harden on impact.