as much as i agree with your first point SirK.
the problem would also be that while many people arent aware about those "default" settings, they will probably not also be aware of the existence of linux or other OS. At least IMO, many people see the bugs of windows because a majority of people use windows. If the same amount of resources are placed into other OS in discovering weaknesses and bugs, I am fairly confident they will have the same amount of buglist that can be discovered.
another note is i belive would be a good but decieving advertising being made by MAC
http://www.apple.com/getamac/ads/
especially claiming that thier OS is spyware free and cannot be hacked into.