Belly button hole is outie. Is it worth going through surgery to make innie?

Not necessarily. Not unless you are bothered by it.
Maybe. If the surgery would be purely for cosmetic reasons, then that is purely a personal decision. If you have an umbilical hernia that is causing a bulge, and if it is enlarging or uncomfortable, then surgery can be performed to repair the hernia and return the belly button to a normal visual appearance.