Why do some people regard nintendo as "kiddy"

I don't find them to be kiddie, I just think they are designed to have mass appeal. Just like a G-rated movie is made to appeal to 'general audiences', a lot of Nintendo's games are made to appeal to people of all ages. But of course, there are ignorant people out there who think G-rated movies are only made for kids, and Nintendo games the same. They're are not skewing to a younger crowd, but rather a more general crowd.

And even if they were making games for a kiddie audience, who cares if they're still good games? Regardless of people's personal opinion about them, they still manage to get good reviews (from critics who are mostly adult), good sales, and a loyal fanbase (composed of people of all ages). If you want to hate on someone for making kiddie games, at least hate on the developers that flood the market with low quality games designed around stupid characters (Nickelodeon and Cartoon Network characters) instead of good gameplay.

Jam it back in, in the dark.