actually, this hero is quite needed to speed up the army's movement. if u take the 'organized' trait, get some items/spells that increase movemet, or use teleport spells, u can move those powerful but slow unit fairly easily. mobility is, quite frankly, the only thing heroes excel at late game. however, having a hero with ~30 hp, 60 attack and 100 def isn't that hard, and atm i can't see how a caster beats that, when spells miss most of the time..
i hope that devs will put some thought into all those aspects in near future. it will surely take some time and effort to straighten everything up, but we're not in any kind of rush, aren't we? 