I wouldn't say that those are the best examples for claiming that times have changed.
Yes, in World's Most Evil Invention, they treat the subject as a joke - but the punchline is that all the evil-doers can't imagine something so evil.
And as for the Teacher Trial skit, that sort of joke is nothing new. Southpark did a whole episode where Ike got molested by a pretty teacher and every man in town, when they find out, says "Niiiiiiiice!"
However, it is a positive thing that the issue is being treated with humor rather than the exaggerated seriousness it was often treated with in the past. I have even seen some recent material questioning the way in which every 80's sitcom had to have a serious "special episode" that frequently displayed a cure that was worse than the disease.
As for SNL, I suggest you look up "The Jolly Trolly Allows Underage Drinking" (in which two "gerbils" - the opposite of cougars, two ten year old girls who like older men - get the attention of the protagonists by buying them a round of drinks), and "Meet Your Second Wife".