I don’t understand what’s so bad about cows milk?

We’ve been drinking it for generations but all of a sudden there’s this new trend of not giving toddlers cows milk anymore.

I’m not talking about if you have sensitivities to it or are lactose intolerant. I’m just talking about moms never trying it and making like its poison when we’ve all been drinking it this whole time.

I know cows milk has the fats and calories needed for toddlers especially if you have a picky toddler. So....what’s so bad about it? Educate me please.