You make some good arguments so I’m not attacking you at all, just my thoughts on your points. These short renewal times are getting to the point of ridiculousness and creating another point of failure with little time to do anything about it. I find these super short certs less than useful, create many more possible problems, and not really necessary except for a small set of circumstances. And I have been in IT as a web dev/sys admin/systems architect for over 30 years now.

• If a private key leaks you’ve likely done something wrong. Practice better key management and don’t be stupid
• Updating certs to keep up with new crypto standards is useless. For one they don’t change that often and if there is a pressing reason you can’t update earlier.
• Yes the processes have to be automated which is not a bad idea at all. But you are completely relying on the service to not be down and that something on your end hasn’t also broken. Anybody that hasn’t ever been a sys admin has had several automated process die for no apparent reason.
• This could actually be an issue but totally out of your control. This is only relevant if you domain hop frequently and if your that worried about security, you aren’t doing that.