Couple of things.
First, it almost goes without saying that lists like this are inherently stupid. Not that that has prevented me personally from making them, or complaining about those I run across. There will never be a top-anything list that everyone will agree on. Hell, I can't even make a top-anything list that I would agree with myself after a little time passes--especially when the criteria are things as subjective and prone to mood swings as "most depressing." People mainly throw these lists out there to support some agenda: riling people up, "proving" how smart/cool they are, getting attention, making a buck, whatever. The lists themselves have little or no intrinsic value, unless you count the ability to provide entertainment for people taking potshots at them. Which we all love to do.
Second, though, is that this list is particularly stupid because it mashes up about five different shades of meaning for "depressing," and to no good effect. There are torch songs (one of the most fabulous varieties of song, IMHO) that just rip your personal emotional scars open. There are maudlin songs, which use any cheesy trick to try and pluck your heartstrings (sometimes successfully, sometimes with unintentially comic results). There are desperately clueless songs, which are depressing in the sense that you feel ashamed the human race is capable of such drivel. There are songs whose lyrics are about depressing topics; they might actually be uplifting if there's a moral to them and some that could be almost jaunty with a few words changed. There are songs that put you in a foul mood because the artist has obviously gotten away with something, foisting such a piece of crap on a population of ADD-afflicted record buyers. (If you want to start a new list of all the flavors of "depressing" that music could embody, I'm sure this community of aficionados could add some beauties.) Whatever minimal coherence the list might have had is pretty much ruined by the mix. The guy didn't even bother to make interesting juxtapositions.