I think there's something we're missing that we can figure out from the books we have though. So far, Brandon's been really good a subtley forshadowing things, making very important things seem very unimportant, often just mentioning them in passing once or twice and then coming back to them later. I'm sure there another secret left to uncover that's in the already published books.
Then again, "there's always another secret."
Modification:
Ok, I've been rereading this thread again, and something jumped out at me. A little earlier there was some talk about the well holding the power of both ruin and presercation and that the hero got to decide. I'm not sure if this has been touchedo n, but it pretty much says this in the book. In the passages about the prophecy I'm pretty sure it says something about the hero bringing ruin in his wake and yet bringing stability or something like that, wouldn't that be the same as finding the balance? Oh, and I've also been thinking, if Ruin is what was trapped in the well, then why is the power that Vin and the Lord Ruler took the "power of creation." My guess would be that the power is not of ruin or preservation, because creation is neither really, preservation is lack of change, ruin is destruction, so would that mean there is a third party? Brandon seems to like threes. Three created creatures, three magic systems... Oh, and have you noticed the magic systems sort of have their own affinity for ruin or preservation. Feruchemists are very much preservation, they store and preserve knowledge, while the Inquisitors, who we know have something to do with hemalurgy, can hear the voice of ruin, does that mean allomancy has something to do with creation. Forgive me, I'm rambling, and not spitting out anything conclusive, but what if Creation is the state of balance between ruin and preservation? Just some food for thought.
And is it jsut me, or is ruin not the only thing that is bound, if ruin is so powerful, and there is supposed to be balance, shouldn't preservation be powerful too, however the mist spirit doesn't seem to be overly powerful, and is unable to speak, maybe ruin and preservation trapped eachother, preservation sealed ruin away with its opposite: creation, and ruin trapped Preservation in the mists, maybe the mists are just ruin's tools, and preservation is trapped wihin them, again, I'm not even sure, this is just the sound of me rambling and my head exploding