Earlier quoted context omitted.
Why would all your services have to be hosted in house and why would it prevent you from "exposing internal services" (I mean, apart from the fact that they kindof aren't internal services anymore from that point on)? For one, there is no problem hosting your own services elsewhere and having them use your own certificates. But more importantly: Why should your own CA prevent you from obtaining certificates from an e…
The big issue was identifying all the impacted services, reconfiguring all of them testing and redeploying them. If it’s a few services fine. But once it’s a few hundred it’s a pain.
And also, if you have so many services running that swapping out all of the certificates is a major headache, your primary mistake probably was that that wasn't automated? When keys are compromised, you should be able to reprovision anyway.