Well sure, but there are also a lot of nice things in this world to be positive about, and dwelling on the bad (at least in the ways that I perceive) isn't a good way to actually fix it.

I suspect, as knb mentioned, that a lot of this sort of thing comes from the fact that it's very easy to appear cynical, sarcastic, and jaded, and this attitude wins upvotes for a certain kind of facile wit and protects oneself from trolls.