All we know for certain is that that there's something down there that either they - or a group working apart from them, at this point - want us to get our hands on. This isn't the only village with a tunnel system, but it's always been implied that there's something different here.

Whatever the case may be, we need to be sure that our choices are for our benefit, and not one made in haste. If we are lucky, we'll be able to crack all the needed codes - but it does take a long time. That's why we need to be more sure of what we're getting into.