Zelda in particular is a series that I think is great for people of ALL ages to play, no matter how old. With games in general I don't think there should be some mental cut-off age where people think you should no longer play them; they're about having fun and doing something you enjoy, and everyone should be aloud to do that.
That being said, my father enjoys Zelda, Pokemon, and other games in his SIXTIES, now. If anything, he may put in more game time than I do on the average week. We've even had some entertaining times introducing family in their seventies to Zelda as well. They enjoyed it. Obviously I'm going to live by my father's example by enjoying what you love for as long as it brings you joy.