I went to bed thinking about Walt last night. No, not that way - sickos!! And as I always do, I did some research on the real life person who shares his name...sort of. Walt Dawson (which is what Lost Walt's name should really be, and which is his Grandfather's name) is a person, who was born in Portland, OR (Yes, Portland - again) in 1982. As a child he became an advocate for Alzheimer's Disease, because his father was stricken with the illness. It's common knowledge that the most well known symtom of that disease is severe memory loss. Just like the Lost Walt, Walt Dawson was a very "special" child. At age 9 he met with the House of Representative and the President & VP of the United States.
Now looking at Lost, I think that all the children were on the list to be taken by the Others because from a spiritual point of view, they as children are already enlightened. The Others, using the original experimentation centers set up by Dharma, use children to understand goodness in them. However, even though Walt is a child - he is not pure like the rest. He has had to deal with many harships in his young life - divorce, estrangement from his Dad, the death of his Mom. There is a chance for him to become a bad person. So, that's why I think the Others treat him as special - they want to save him from becoming a bad person. It is also why Ben allows him to leave the Island, because by the time he leaves Room 23, he is enlightened and saved spiritually. Perhaps Ben also wants him gone, because he sees Walt as a threat to his leadership in the future.
This line of thinking also led me to reconsider the Dharma vs. Others vs. Hostiles questions. Perhaps the Incident involves DI straying from the reason they came to the Island. Perhaps once they set up a traditioanl society - with laws, and jobs, and punishments, they turned away from spiritual goodness and towards the "dark side". And that's why Ben had to get rid of them?