Because it's fun
Whether it's following an injury or several months of inactivity, getting back into sport is never easy. What with a lack of muscle tone and motivation, and even a few extra pounds weighing you down, plenty of people are scared off.
To avoid the mindset of "I can't", it's important to do something that will give you an instant feel-good hit. Skating is less harsh on your body than running, and certainly more fun, so it's ideal for this purpose. With its sense of freedom and lack of constraints, anyone, of any standard, can do it. It's a fun way to reconcile yourself with sport. It's also a cheap option that's easily accessible, can be done either alone or in a group, and helps you quickly gain self-confidence and the ability to accept your body.