The reason was partly cleanup and it was on my list for a while.  I talked to the Hibernate team a while back about the change nd we agreed that envers didn't need to be in a different module (if a user wants to remove envers, they can remove it from the Hibernate ORM module.)   This gets rid of a hack in WF8 as we don't have to inject the envers module into JPA applications anymore.  Other reasons is that envers has a bi-directional 1-1 relationship with the Hibernate orm module (envers is on the Hibernate orm classpath and vice versa).   

AS7-928 was the original integration jira, for that implementation, we tried to make envers optional which means that the user could delete the envers module but that wasn't an advertised feature (AS7/WF8 documentation doesn't recommend that users should/could do that).