I believe the low maximum lifetimes are becoming a thing because revocation failed.

CRLs become gigantic and impractical at the sizes of the modern internet, and OCSP has privacy issues. And there's the issue of applications never checking for revocation at all.

So the obvious solution was just to make cert lifetimes really short. No gigantic CRLs, no reaching out to the registrar for every connection. All the required data is right there in the cert.

And if you thought 47 days was unreasonable, Let's Encrypt is trying 6 days. Which IMO on the whole is a great idea. Yearly, or even monthly intervals are long enough that you know a bunch of people will do it by hand, or have their renewal process break and not be noticed for months. 6 days is short enough that automation is basically a must and has to work reliably.