I feel like immortality would be one of those monkey paw things... like you get what you wish for, but it's really a curse. With time travel, one could use it to make their life more enjoyable, not just longer.
Would you rather have allergies, colds and "the flu" just as often as you normally did for the rest of your life (which can be dangerous as you get older), or have an invasive elective surgery that would cure you completely?