I think one of Pratchett's great skills in writing was being able to make silly things serious, in different ways. Like, there's a fairy godmother forcing everyone into fairystales, how fun! Except in the process, she has stopped seeing them as people. She's forcing people to live lives they don't want to because she decides that's how it has to be. Sometimes she goes so far as to violate her victim's minds and deform and puppet their bodies so they'll play their part right, and anyone who doesn't do their job gets mercilessly killed. And there's a zombie activist named Reg Shoe who buries himself every year out of solidarity for the dead, how funny! Except he is filled with a genuine passion for justice and improvement in the world, and that's why he literally refuses to die. And he buries himself on a holiday that happens to be the anniversery of his own death, and he does it next to the bodies of the friends and strangers he fought alongside, the ones who didn't get to come back, so he spends one day with them. There is still a lot of silliness in discworld, a lot that's wacky and funny, but a lot of it, when you think about it, is oddly beautiful or touching or disturbing or something else entirely.
