Cougar would be great, maybe they are not used in the opening days of a war, which are simulated in the game (mostly), I don't know. But there are scenarios that play after the occupation, too.
(1) I would like to see Makarovs (the pistols of red vehicle crews and officers). Yet their shooting is simulated, but they aren't modelled, instead the soldiers (graphically) have rifles. The panels show M9s instead of Makarovs.
(2) The possibily to let "acquired" equipment in the vehicle, if you don't need it. For example you equip a stryker infantry squad with many javelins and then most enemy armor is destroyed and you want to move the infantry squad over a long distance. Since carryig 4 javelins slows down it would be better to let them behind in the Stryker, again.