Unless I'm mistaken, the two are not the same. There is a middle ground possible: a developer can publish their own sandboxed apps.
This would get you about half of his "buy non-sandboxed apps directly" advantages (More/Faster Updates, Less Risk, More Money), while still offering the user the advantages of the sandbox (e.g., I can see that a graphics program I downloaded only uses the entitlement "com.apple.security.files.user-selected.read-write" and thus can't open network connections behind my back).
Why? Because of exposure app store gives you app, and far more people would buy it from app store, as it doesn't require you to enter your credit card number in some random, no-name developer' website.
This would get you about half of his "buy non-sandboxed apps directly" advantages (More/Faster Updates, Less Risk, More Money), while still offering the user the advantages of the sandbox (e.g., I can see that a graphics program I downloaded only uses the entitlement "com.apple.security.files.user-selected.read-write" and thus can't open network connections behind my back).