I mostly agree with you and the cynical in me says it's all about greed, except regarding expiration: nothing is eternal, especially considering crypto, so it's

I mostly agree with you and the cynical in me says it's all about greed, except regarding expiration: nothing is eternal, especially considering crypto, so it's a safe assumption to say that nothing can be guaranteed for more than a given number of years. If you don't put a limit, you stall development of new primitives because deployment is more expensive than deprecation of what is already existing. Putting a "best before" date keeps everyone's head up. The CA system looks like a good idea on paper if you keep it technical; if you look at it from a more widespread angle there's little surprise that it turned out to be like it is. But the idea remains good.