Having a spiral galaxy with homeworlds at the end of the spiral would be totally unbalanced, unless you have 11 arms of the spiral. But having all the homeworlds in the center, and maybe a capture the planet type of behaviour for the last planets on the arm... Having shapes just for the sake of having different shapes is not something worth implementing. Maybe resubmit this idea with scenario ideas and they might implement it.
Having a spiral galaxy with homeworlds at the end of the spiral would be totally unbalanced, unless you have 11 arms of the spiral. But having all the homeworlds in the center, and maybe a capture the planet type of behaviour for the last planets on the arm... Having shapes just for the sake of having different shapes is not something worth implementing. Maybe resubmit this idea with scenario ideas and they might implement it.