This doesn't matter now. People don't (and sometimes cannot) upgrade quickly. Also, documentation for the latest version still says peer_verify defaults to false and CN_match doesn't mention being computed automatically.

Effectively if you write any code you're not going to deploy yourself, you have to specify the CN_match and verify_peer. Others will not know about the limitations, so this function is messed up until after 5.5 is EOLed.

Designing APIs is hard and bad defaults can hurt for many major versions after they're changed.

Not before 5.6 (where CN_match is actually deprecated in favour of peer_name)

It is? Which of the versions of PHP linked from the homepage of PHP.net do this? I didn't think any of them did.