But really, we should go all-out: Allies use NATO counters, Axis uses German symbols, Comintern uses Soviet symbols and neutrals use Paradox's pictographic counters
As I recall, the Germans changed their system of symbols in 1943...maybe that can be covered in the national focus tree.
But seriously, the new map system is objectively better than the old system, you couldn't see anything more than the unit on top of the stack in HOI III, you had to mouse over the stack and look at the tool tip to get useful information about the units in a province, now you can see it at a glance. I think the problem isn't a lack of counters so much as that the sprites just aren't that good; they professional, well polished, and nice looking models, they just don't convey a lot of information at a glance and look similar for very different unit compositions. I'd prefer it if the sprites were small formations, if you had a unit that was half armour, a quarter infantry, and a quarter marines, you'd see half the sprite as an armoured formation, a quarter as an infantry formation, and a quarter as a marine formation, conveying graphically the unit composition at a glance. Of course, this would be several orders of magnitude more art work, which is probably why they didn't take that approach, but, still, would make good DLC.