MAR's are better for soloing until they get steel cyclone so it may be difficult for someone who is leveling their WAR to reach the level that steel cyclone is available. I imagine there are other such issues for some of the other classes too so they shouldn't just get rid of the lvl for MAR past lvl 30. Plus there is no harm in keeping the system how it is? It gives us more freedom since if we want to just play as MAR and never even touch WAR, we can or if we want to pretend our character has ranked up into a WAR and never fight as MAR again, we can do so also.