I believe fuel costs on call-ins is a problem, because right now it forces you to go Tier units or doctrine units, in CoH1 you could get Tiger in late game for 800 MP and that was fair and you could get some other tanks too from tiers, CoH2 is one sided in terms of tiers, call-ins or tiers, never both (talking about small matches like 1v1)
Another thing is, in coh1 call-ins were side grades or different role units. In coh2 they are plain upgrades over tier ones, so there is even less of a reason to go stock units. Couple that with ineffectiveness of stock armor(especially for soviets) compared to call-in one and we have current meta.