But maybe the point is that Our Heroes™ don't
know how everything will turn out. They might think
they do, but all evidence so far suggests that they really don't. For example, it looks like the attempt to stop the Incident from happening will be the very cause for it to happen. Or Sayid, he thought he could change the time with killing Ben in the past, but it seems like he only furthered his bond to the Hostiles.
I agree that all of this would be tedious drama if they (and us) would already know how everything will turn out. But the thing is, we don't know what will happen. As Daniel said, this is the Losties' present. They can
die. And I think that makes it all the more entertaining.
But I guess we will just have to wait and see.