We know that Richard work(ed) on other Arcana cards.
If we look at other C&C games, army specialization stuff are : global special rule (Activation of one more unit for Americans in Pacific theatre, Goblin rush), special troop (Alexander companions, Bagpipes) and perhaps special Arcana.
In my opinion, Command cards don't have to change. They are, with 3 sections boardgame and special dices, the backbone of C&C system.
The real problem is the total mass of rules.
More special rules means more exceptions and FAQ, more things to keep in mind.
I would prefer less new units but high tactical potential ones (more like Goblin orchestra than Dwarf Axe Swingers) for real dilemma, no new units only for have more units.
So classical weapon like pike must be used by new races (less special rules to learn) and few special tasty units.