We know, we were confused when we saw it, too. Some random arrow with "Here's The Drop™" being placed all over our SoundCloud sounds - especially when they're placed in random spots? It came out of nowhere, and smelled like a cheap cash-in of the EDM craze. Then we remembered two things: 1) the SoundCloud developers are from Sweden, and tomorrow's April Fool's Day. And while it's not techincally April 1, even in Sweden or Germany (where SoundCloud was established), we're going to assume that this is an early April Fool's joke... which seems to have gotten people upset. Even artists like Om Unit, Cashmere Cat, and Halp are seen venting about what appears to be a sudden change SoundCloud has done for no real reason.
If anything, this shows how dedicated people are to SoundCloud, and how they don't want the developers to mess with what's already working! Hopefully this doesn't turn people away.
UPDATE SoundCloud has posted about their "Dropometer" on their blog.