There's absolutely nothing wrong with calling things "kiddie" unless you're insecure... I into my adulthood own tons of toys and enjoy many games of every rating... currently enjoying Portal Knights on my Switch which is indeed kiddie! When I get back home to my PS4 Pro I'll be continueing my playthrough of Knack 2, and Crash Collection that are both kiddie!
My entire living room bless my wife for letting me have this room to decorate is a fucking kiddie wonderland! And I wouldn't have it any other way!
On my worst days when I need a good laugh I'll put in my DVD copy of Heavyweights or the original Power Rangers movie because they are both things I cherish from my childhood both are Kiddie... just got done watching my favorite Xmas movie with my Wife and In-laws which is Jingle All the Way... a very kiddie Christmas movie... when I'm on my days off and my wife is working and I have the TV to myself I'm watching Avengers Assemble, and other Marvel cartoons or rewatching X-men, Spider-Man, and Batman TAS from my youth.
The difference is I don't give two shits about people labelling the things I love as kiddie because I am a grown man who does not get insecure over what people label the things I enjoy.
As far as I am concerned anything that's rated E-E10, and even some T games are kiddie, and I love them. And a lot of the movies and shows are kiddie and I love them! The word is too serious and I cherish things that are whimsical and lighthearted but they are still kiddie... now if the label was "childish" then you'd see me on the other end of the argument but kiddie =\= childish.