My understanding is that currently, command roles are rolled for before crew roles, and by extension, antagonist roles. For players who enjoy being an antagonist, this can make playing command somewhat unappealing.
Playing antagonist is a somewhat rare occurrence even if you only play roles that can be antagonists. By enabling command, this makes it far rarer. Not only does it add roles that can’t get antagonist to the pool, but those roles are far more common, due to it being decided before crew, and the relatively small amount of people with command enabled.
I believe if antagonists were rolled for first, it’d make command roles far more appealing to a lot of people.