Not needing a python interprter and setting up cron jobs? The sole reason for using Caddy really, because it's just install and forget. I never had an expired certificate with it. I don't want to mess with an entirely different webserver config either after having fully configured my nginx instances. Too bad they wrote it in rust instead of C, now I need another compiler to build it. Minor nuisance. Hopefully it will get packaged.

One less program to install, configure, upgrade, watch vulnerabilities in, monitor.

All of those things also apply to this module since it's an extra module that you have to install separate. It's not included with the nginx base distribution. You have to configure it specifically, you have to monitor it. You have to upgrade and watch for vulnerabilities.