Great question, as always. The wear of Command Badges was started (a very long time ago, likely rooted around the time of Unification) to provide a common and shared identity amongst members of an organization. The Dress Policy dictates that each member of the CAF will wear a Command, Force or Formation badge on their Ceremonial/Service Dress. Further to that, it is directed that the Command Badge which is worn must indicated the organization in which a person is currently serving, which ensures that people represent their employment, rather than their environment. To make a long story short – it’s about a standard (equal) approach to insignia on the uniform and displaying the team identity.
If you think of our “purple” occupations working at our Division or Wing, it would look really odd to have a RCN HRA wearing a RCAF Command Badge standing alongside their RCAF HRA coworker who is not wearing a Command Badge, solely because they have a different colour uniform. An equal, or “uniform” (no pun intended) approach is needed to ensure that we do not single one member out over another.
Hope it helps.