Why is it beneficial to be able to regenerate parts like the planaria worms?

Unlike humans, the planaria worm has the ability to regenerate its lost body part naturally.

I think it is beneficial for humans to have the ability to regenerate body parts like planaria worms for a couple of reasons. One would be to regain a body part that could have possibly been lost in a tragic accident. Another reason would be that it would save humans from financial burden in the case that they incur medical expenses to be able to replace what they have lost.  In addition, I believe that the human race can have longer lives should they have this remarkable ability.