Apple Mountain Lion - Security Excuse

It's known that MacOS and all other Unix based systems are very safe compared to Windows based system.

But I think it's genius to use security excuse so developers have to publish their apps to Mac App Store. Imagine all new users using the ultimate security level - Run only apps from App Store.

The only option to run an app in a practical sense is to publish to App Store. You could also make a tutorial to your users about how to change their security level. I wonder if they will trust you.