Reduced certificate expirations also enhances the security of the internet as it reduces the window of opportunity for nefarious uses. It could possibly reduce their number of support calls from someone who's taken over from a previous admin and is now faced with an undocumented manual process to replace certs in a hurry as their website has an expired cert.

Personally, I don't see the problem with short expiry dates, though less than a month would be too short in my opinion.