So in order to show the importance of this security update, they've put it in bland writing in a long, detailed security notice that only the most ardent of admins would read thoroughly, and even then it doesn't particularly stand out as important.

Regular Jane and John Does or even power users would have no idea of the importance of upgrading their system for this. "500MB update? Nah, it can wait, I don't need any of that".

Nice call. Yea very strange. Seems like the most important thing in this update. It should at least be at the top of the bug fix list.

It might also be last in line since it was last to go in to the release.