To me,

The "feature pack" is something for the WildFly build to consume

is different from

makes it easier for the application server to load/fetch this on demand.

The former applies at build time of WF, whereas I understood the latter to apply at runtime (or maybe at configuration time of a WF install). If a feature pack is something which can be used to create a tailored "distribution" of WF, it seems not useful for us atm.