Being able to Regenerate Parts, Beneficial?

It would be beneficial to be able to regenerate parts like planaria worms because then there would be no need to suffer and be in pain in order for something to heal. Also being able to regenerate can help the death rate decrease and allow us to live longer than the regular life span. However, being able to regenerate parts means that it would also take a long time and could be painful to look at or bear making the idea of being able to regenerate parts not beneficial. Even though the whole population may benefit from the ability to regenerate parts of the body it may have bad effects too.