I don't think you can say this in general. There are a lot of uplifting chart songs. On the point of substance abuse, yes, that's a topic. But in reality, young people just tend to talk about this and it's really hard to say what's cause and effect.

And I really can't see your points about superficiality, racial stereotypes etc. That niche surely exists, but it's far too hot for the big labels.

Lastly, on anti-intellectualism: Yes, those songs tend to not be too intellectually challenging, but I don't think that's bad. People tend to listen to those when partying or just relaxing ; it's okay to simply chill out sometimes. Most people don't want to read technical literature for coming down either and that's fine.