But overall I agree with you. If everyone is fully vaccinated, wearing the mask whether indoor or outdoor should be a personal choice, especially since there will be reduced capacity, social distancing and other health measures.
I've been cautious and pro-mask from the get-go. We ordered them before everything went crazy, and you couldn't find anything. I've followed the rules with no objections, and generally would rather err on the side of safety because it isn't a huge deal to me if I have to wear a mask for a bit. Minor inconvenience and all that. I say that as preface to saying I absolutely agree with you here. I would have zero problem sailing on a fully vaccinated ship. Even if there were breakthrough cases, your chances of catching it from other vaccinated people AND then getting even close to severely ill are super, super small. I wish the CDC was a bit better about messaging how vaccination can get us back to something really close to normal, but things like their rules for cruise ships do not help that argument. Time will tell. Hopefully, we will be back to something approaching pre-pandemic times by next summer.