South Park is one of the cleverest shows on TV. The way that it approaches world issues, creates extreme arguments on both sides and the conclude with balance is actually a really important tool for people to see issues from different perspectives.
Also, Cartman as a character is probably the most advanced character in all media - the way he is designed allows him to do literally anything, be completely evil and trivial at the same time, and allows the show to explore really intense issues in ways that no other show has been able to do (maybe until very recently).
I'm not really a fan of the toilet humour but South Park is so much more than that - I'm so glad it's still on.