I make constant fun of people's stupid Lost theories, how they're based on little evidence, stupid conjecture, and the moronic sci-fi they've encountered other places. Like that would stop me from trotting out my own stupid Lost theory.
I propose that the Smoke Monster orchestrated the return of the Oceanic Six and Ben to the island. Why would he do such a thing? He knew he could use Ben to kill Jacob and could use Locke's form to convince Ben to do it. Island rules required that their return be as similar to the way they originally got there, hence the necessity of as many of the Oceanic Six going as possible. Smokey needed Locke to get off the island and act as a recruiter, saying he was going to have to die. He did this via Richard Alpert when Locke was flashing through time and FLocke had Richard remove the bullet and deliver his message about getting them back. Smokey needed Locke to leave the island, die, and come back - that's why he had him move the island in the first place.
When did that happen? In the episode "Cabin Fever," Hurley, Ben, and Locke go looking for "Jacob's" cabin. They decide the Locke should go in by himself, where he speaks to "Christian" and sees Claire. Locke asks if "Christian" is Jacob, to which he's told, "No, but I can speak for him." This scene should give us pause for a few reasons. First, in "Ab Aeterno" in season six, Jacob appoints Richard as his sole intermediary, so anybody else claiming to speak on his behalf is a liar. Second, it's the Smoke Monster's modus operandi to appear in the form of people who are dead on the island. Third, who is hanging out with "Christian" but crazy, crazy Claire, the same Claire who said to Jin, "That's not John, that's my friend" (i.e. Smokey). "Christian" later tells John that Ben wasn't supposed to move the island, he was. Smokey needed Locke off the island, not Ben.
To summarize: Smokey convinces Locke to move the island so Locke would be transported to Tunisia in order for Locke to die and come back with the Oceanic Six. Ben intervenes, moves the island and is thus banished, screwing things up. Smokey takes corrective measures, leading Locke back to the frozen donkey wheel. Locke goes back to the real world, fails to gather the Oceanic Six, tries to kill himself before Ben murders him, and the Ocean Five, dead Locke, and Ben go back to the island. Smokey, now FLocke, convinces Ben to kill Jacob. Then Ben kills Jacob.
Think I'm crazy? Consider the when they get inside Jacob's dwelling in season five's "The Incident", FLocke tells him, "You have no idea what I went through to get here." I formalized this theory and then ABC release this clip for next week's episode.