A microservice runs as some (somewhat) privileged user, you may want some auth. Can everyone internally create sales tickets? Or can everyone just query them? If a team provides a library to run, and you run it, you still only run as whatever user you have access to.
Monitoring: it's easier to look at a stack trace, including some other team's external library, than a HTTP error code 500.
Deployment is certainly easier when you're just shipping code and a build. You don't have to faff around with the previous instance running, maybe having some active connections/transactions/whatever, needing to launch a new one. Maybe it's not hard overall, but less fun.
Monitoring: it's easier to look at a stack trace, including some other team's external library, than a HTTP error code 500.
Deployment is certainly easier when you're just shipping code and a build. You don't have to faff around with the previous instance running, maybe having some active connections/transactions/whatever, needing to launch a new one. Maybe it's not hard overall, but less fun.