Ok here's the deal. All they have to do is make SMN dependent on MND for one reason. That way no matter what you do, you will always have one dps class, and one healer class available to you. BLM/SCH = INT SMN/WHM = MND

That way there is no need to scream bloody murder about spending 10k GC seals every time you want to switch between heals and dps.