I have a parent, and I imagine many have one like this, who stubbornly thinks that anything animated is/should be for kids.
Its annoying and infuriating because it undermines and trivializes entertaining, creative, and good writing.
I don't know if it's because that sentiment is hardwired into their brain, or if it's because they're just a cliche product of the baby boomer generation, but people that grew up 20-40+ years ago did not grow up how people in the last 15 or less years are growing up. Our technology, entertainment, social lives, ideals, economy, even our diets are radically different from the 70s-90s.
Today I find myself still into things from my childhood that I felt like I "just gets it" compared to something that felt like a phrase/fad. As a kid I liked Pokemon Red, love Pokemon the show, and was obsessed over collecting Pokemon trading cards. Now adult me loves the game and shows little to no interest in the rest if the franchise, but then a spark lit inside me about the Trading card game, when the online version taught me how to play. When I myself understand and can see /still see whats so great about something from my childhood or in that matter, anyone else's childhood, then the question of "am I too old for this?" never comes up,
Replace Pokemon with anything else like a specific show, game, food, music or whatever, and my ideals are all the same. I'm too old for for Chef Boyardee because as a kid it was the greatest thing ever, but as an adult I can see how godawful disgusting it is.
I guess it might also depend of how critical or stubborn you are as well. Its hard to see the bad in things as a kid, because often the case that "meh" or "good enough" is more than adequate.