What I find interesting is that such humour isn't the product of the late 20th / early 21st century, it's not at all new. It has been around for decades in absurd art, I can see the connections. (And I would risk saying it has always existed!)

So the question is: are we really becoming increasingly stupid? Is there really a tendency? How stupid can we get, if (e.g.) playwrights in the 1950s have already been making attempts to point out the phenomenon of being stupid?
Maybe we have never been clever, maybe humans have always been so stupid (while thinking they were smart), maybe we are only able to find new ways for being stupid, and art (or at least some of it) has always tried to underline this basic characteristic. (I wouldn't call my opinion pessimistic, it's rather realistic.)

Thus we can admire the artists' creativity, how they adapt to contemporary life, but we should not think that the message is something essentially new. (As there isn't much new under the sun.)

Don't get me wrong, I like the ideas, it does add something new to the old discourse, and it does speak about contemporary society, culture, etc. But we shouldn't forget it's predecessors.