Mac OSx security features missing

FWIW, this is a users forum. No one here would have any insight into Apple's decisions.

If you check for software updates and it reports no available Apple security updates then one can conclude you are fully up to date. A less friendly method would be to look in /private/var/db/receipts this contains 'receipts' for all previously installed installer packages including all previously installed Apple Security updates.

Note: If you install some OS X updates this may often include security updates as well.

With regards to securing System Preferences. If you go to Security & Privacy, then if needed unlock it, then click on Advanced, you can tick (enable) an option to require the Administrator password for system-wide preferences i.e. those controlling more sensitive options. Once unlocked System Preferences will normally remember it is unlocked but only for a short time and if you quit it then re-open it, it will be locked once more immediately.

Hold down the option/alt key while selecting the  menu. Select the first choice of System Information (exact name depends on the OS you are using). Then look at Installations in the report to see what is installed.

Like wise you can go to the App Store>Updates and see your last 30 days updates, including security updates.

If this does not satisfy your needs you can send feedback directly to Apple.

I would encourage you to do so to make your voice heard:

Apple Feedback http://www.apple.com/feedback/

addendum:

New security features have been added independent of the default lock in System Preferences>

Security & Privacy>Privacy>Advanced>Require an Admin psswd to access system-wide preferences

see OS X: About Gatekeeper - Apple Support

About System Integrity Protection on your Mac - Apple Support