It is a combination of "many eyes" and "good documentation". What is needed is some good text that describes the design choice, the rationale, and all the tricky details; and then people who read it and think about it. I'll write and publish such text within the next few months.
Generally, open source software benefits from more users. But having a huge amount of users makes it more difficult to improve and cleanup because you can't just deprecate stuff easily. (like SSL2/3).
Also, having 100% of the internet using openssl makes the impact of a vulnerability in that library huge. Some diversity is probably a good thing.
I appreciate the time and effort that you are putting into it, good luck.
