Innistrad block was a successful experiment in many ways: As the first truly top-down block, it took the leap of putting the mechanical theme (graveyard stuff) in the backseat and also letting unrelated mechanics have some of the limelight. One of these was using the existing mechanical technology for enchant player Auras and making Curses to fit the Gothic-themed spooky world.
Even though they weren't the main focus, Curses have had at least some casual and EDH popularity - witness many a wacky Curse of Echoes combo deck - and they did come back with a cycle of five original cards in Commander 2013 for the multiplayer interestingness they have, but it's not clear they're popular enough for more beyond that. Mark Rosewater, however, seems to think so.
When cobalt127 asked, "How popular were curse enchantments in the Innistrad block? Can we expect to see them in the future?" Rosewater responded:
They had their fans. We’ve already brought them back once and I assume we’ll do so again.
Of course, having them back for the inevitable-because-of-the-popularity-of-the-original Return to Innistrad block is the obvious answer. But what do players really want them for? The type exists largely for flavor, with a few mechanical interactions, so top-down is indeed best for your average Curse. So what other places would be full of horrible pernicious Curses on players themselves? They fit reasonably well in Zendikar; but no doubt many people are thinking what kobayashicircle is thinking: "EGYPT BLOCK EGYPT BLOCK."