It doesn't matter if you are in Seattle, where it drizzles non-stop for 24 hours a day, or in Panama where it doesn't rain long but comes down extremely hard. If you have a metal roof, at some point you are going to have to perform a metal roof repair. And preferably you deal with it before you have to suffer with a leaky roof.
Generally, when a metal roof has physical damage resulting from hail, the roof's protection of the structure remains the same as it did when it was new, whereas other roofing materials often have "hidden" damage resulting from hail. Unless your roof has suffered damage resulting from a very severe hailstorm, the decision on whether to replace your home's metal roof due to cosmetic damage is usually a personal decision, most likely not covered by insurance companies.