Configuring JVM metaspace is generally not recommended; it's simpler to let the VM manage things.

https://access.redhat.com/solutions/1489263

However, setting MetaspaceSize doesn't do any harm and has a small (0.5%-1%) beneficial impact on boot time of a server with no deployments. (The percentage impact would be less with deployments.)

The basic reason to remove MetaspaceSize setting is to just simplify things by removing this entire topic from how WildFly works. WFCORE-7049 will remove setting of MaxMetaspaceSize, which is a separate setting that can cause problems when misconfigured.

Work on this should be done in a separate PR from WFCORE-7049 so it doesn't block that more important issue.