Casual users have no reason to visit maemo.org, it has absolutely no content they could possibly want except perhaps some of the applications in the download section. The downloads can be syndicated though and placed on a site more suited to casual users.
Who is turning anyone away? Casual users can use Tableteer if they want, and then go on to use Maemo.org if they become more confident with their tablet knowledge.
But most casual users will stay casual users forever. They don't want to know more about the tablets, they just want them to work.
Most casual tablet users will NEVER want to get involved with software development.
Where are these newbies? I check the newbie board every day and very few of them turn up. They must exist, but they very rarely post.