I doubt more people will reply to this thread, but here's what I think on the risk of bumping a lonely thread.
It's simply because, when it comes down to it, serious art is a significant reflection of the artist(s) who made it, and most people today do not believe in wholesomeness and "regular happiness." Everything has to be made ironical, edgy, or downright miserable bec. those are the actual lens, consciously or unconsciously, through which they view the world. Additionally, a less-serious reason is that this is the easiest type of humour to make; just think of Family Guy or anything else that gets laughs off of stupid edge.