Why do people say this is 'so much darker' than the first?

But there was also more sickness (Hoggett) and death (the clown) in this film, as well as those shady men threatening Mrs Hoggett in the beginning.

And I disagree, I think violence did make this film darker. In the first film, it was mostly dogs that were violent, either because they were jealous or they obeyed their masters. In this film, a lot of the violence was more 'voluntary' and human-like, like the apes when they mistreated Babe.

An utter lack of coherence should be "dark" enough for 'most anybody.

Because it's so much darker than the first.

I love this movie.