Since MiAB is able to be the authoritative server for a domain, and that DNS server has an API, it would be useful to have DNS challenge for Let’s Encrypt. This would decouple the Let’s Encrypt certificates from the HTTP/S requirement, making it easier to deploy MiAB behind a firewall that intentionally blocks HTTP requests or other configurations that are incompatible with the HTTP-01 challenge.
If you need something for a specific install, you can always use your own tool. The acme.sh project supports DNS-01 and already has the MiaB API (as well as many others). I’m not really sure how to make it work without MiaB scripts causing problems.