As a framework developer I want to change the objects that Shiro loads, so that other developers need to provide less configuration.
(When using a shiro.ini, the ReflectionBuilder processing happens in the IniSecurityManagerFactory, which makes it difficult to add default objects to the object graph. Currently you must extend the environment and a SecurityManagerFactory to override this behavior.
Ideally I think the ReflectionBuilder processing should be moved to an Ini Environment class, but that is not easily done in a backwards compatible way. Therefore mimicking the pattern that the IniFilterChainResolverFactory is probably the safe bet.