I don't think it ever was. It's a form of entertainment much the same as watching a movie or reading a book. It can and has been enjoyed by adults for many years. People who call gaming "childish" are usually people who don't play games (yet most likely still frequently play Candy Crush or Bejeweled on their phones).
Usually people say games are childish because "you're an adult playing games, grow up" and it usually has nothing to do with the games rating. I find that viewpoint rather ridiculous though.
Usually people say games are childish because "you're an adult playing games, grow up" and it usually has nothing to do with the games rating. I find that viewpoint rather ridiculous though.