Make romans cost more. Simple solution to a whole array of problems. Make them choose between units like pantodapoi or lugoae because of lack of money. For ex..i am yet to see 1 unit of vigiles in all games. As for chevroned cohorts , that is just..obscene.

Romans..highly trained ( paid instructors anyone ?) , highly motivated ( expensive to keep them interested) , superiourly armed ( AP , good attack , good shields , are you kidding me?) , low paid ( 120 romans get paid less than 80 naked gauls ).