Capability based security is the natural way to do things in most other aspects of our lives.

We live in a capabilities based world. Most of my outlets give 120 volts at 15 amps and deny access to the whole power grid. We don't have to have certified electricians check each and every device before connecting it to power.

When I want to pay for a purchase I have a number of possible economic capabilities from 1 cent to 100 dollars. I don't have to risk accidentally draining my bank account to pay for a soda.

On our GUI oriented systems, file selections could automatically handle capabilities and the user might not even notice a difference. We shouldn't have to risk our computer just to run a program.

Give that all of this was worked out in the early 1980s, I strongly suspect a conspiracy to deliberately delay the implementation of capabilities by the US NSA and other Intelligence agencies. Ironically this choice resulted in horrible long term consequences for US National Security.