There is a ticket for v11 for reviewing notifications against all privacy settings. Notifications are incredibly complex when all variables are considered.
I think if you would do that, it will cause many people getting upset. It should stay that way. If user A wants to see user B post because user A set privacy level to friends only, then user B can request friendship with user A. If you change it and allow anyone to view any level of privacy, huge mistake, people will not post anymore and leave the site.
Getting a notification from a friend but not getting access to the content is annoying. It's not the privacy settings that need to be changed, it's the wrong people getting notifications that needs to change.