no suppression, no cover, no tank/infantry dynamics, viability of 1 unit spam armies
I realize I'm going off topic but I really don't miss suppression and I'd honestly rather it be gone. It's an awful mechanic when you get down to it and Ancestors doesn't need it with melee fights being locked in until someone retreats or dies.
There is actually cover, there are terrain features that obscure your units and reduce ranged accuracy, but for a mechanic which approximates cover in an infantry fight you have the charge vs. melee defence stance dynamic.
1-unit spam armies are also not viable, I really don't know how much multiplayer you played. The Germans have some trouble in that they lack a hard melee counter to spears but their spearmen are superior and they have enough tools to deal with it otherwise.
There's no tanks, obviously, and it's stupid to expect them but cavalry fill that role nicely with an insanely powerful charge, but they also interact with other units much more nicely than tanks in CoH.