Comic Sans is always seen as a really goofy, wacky font. It stems to it being really informal to use and unprofessional looking. It’s a font you will see on a small sidewalk lemonade stand and not on a multimillion dollar company. The bad reputation only arrives sometimes ago, when the internet starts being widely used.
Before that it was used everywhere, from gravestones, to warning label, it’s seen just an interesting choice of font. The backlash was unforeseen, something you get from the viral nature of the internet, some people hate Comic Sans, and others agree, and it spreads and makes the Comic Sans the infamous font it is today. It slowly becomes the butt of a joke, the ugliest font you can use to offend someone. For a font that was designed based on comics font (if the name itself hasn’t spoil that for you), it’s a casual and ‘fun’ font that shows a care-free attitude, a font that people love to pick because it feels organic, like a handwriting. It’s a victim of a social phenomenon, from a high initial well received success, to an immediate hatred. It’s easily misused and overused. It has its place nowadays, just not in the professional scene. Not anywhere honestly. Guess this is why do people hate Comic Sans so much these days.