Damon and Carlton have, from very early on in the shows production, claimed to have known how they wanted to end the show; stating they had a very visible beginning, middle and end for LOST. 'Adam & Eve' has been cited by the two as being one of the key points in LOST that would hold merit to this claim. The black and white stones found next to the bodies of a male and female long dead by hundreds of years (400 if my memory recalls correctly).
Who else feels like, after tonight's revelation of who 'Adam & Eve' really are (MIB's natural body & the adoptive mother of Jacob and MIB), that the writers are making a lot of it up as they go? Sure, the black and white stones were there (and have been a running theme in the show for quite some time) but that doesn't mean they did not decide this season who they wanted to put in that cave-wall-grave. It would be safe to say that I was let down by the revelation, and felt the ORIGINAL intended 'Adam & Eve' was different from what is now cannon. But that's not what I wanted to discuss.
Discuss: Is it possible that things like "who 'Adam & Eve' were," "the numbers," and "the mythology behind the island" changed because Damon, Carlton and the rest of the writing staff saw so many people backing an idea as to what an answer might be and wanted it to be different or unexpected? Example: "Was it originally intended that they were in fact in Purgatory and then they changed it because so many people backed that idea as the answer?"
I'm not saying the example is a good theory, I was simply using a better known one.