If you read between the lines, it appears like JBoss went with their own module framework so that:
- they could find a way to appease the OSGi community (as they propose that their implementation is compatible)
- support legacy MBean components
- inter operate between various implementations (conjecture: jigsaw?)
It's my opinion that this was actually a wise move, assuming the effort was not very high. This is because Project Jigsaw is still an unknown in the modularization market, and perhaps JBoss is positioning themselves to be one of the first to support it.
As long as I can use some nice OSGi module-based solutions in the meantime, I think this is a big win for JBoss as an App server choice. I'd prefer however for modularization to make into Java via a JCP (and therefore into the JEE spec), so at least there's some kind of standard implementation that can be used (with servers like JBoss able to provide proprietary extensions if desired).