Hello mcurrie, I totally get your concerns and we are aware of the pain points of certificate management in NAM. We totally understand the value of the ACME and the gains it can bring in. Just to give you a background, we had picked this story for a Proof of concept to see the technical feasibility. The PoC was successful as well. I'm not sure whether you got a chance to see that video. If you are interested, please drop me an email and I can share that with you. Due to various strategic priorities, we could not bring this in for you.
With 5.1, we have picked up the huge iManager replacement story which will add REST APIs for almost every IDP configuration tasks. Along with the iManager replacement, we have picked few stories in the certificate management also like multiple signing certificates for IDP, automatic SAML2 metadata refresh, optimizing the certificate renewal process etc. Optimizing the certificate renewal process will definitely look into ACME. Please be assured that we are looking at improving the certificate management experience altogether and I do believe ACME will get in this time. Hope this helps!