you need to look at the total package. You wont pick ostruppen just bcs of the drops. Bcs you dont have anything of use in the rest of the commander in 3v3. With cas and luft supp you do have a lot of good other abilitys (srry for english). Thats why you only can have one of them in yourloadout once, and i didnt do shit about ostruppen
Except for the railway barrage you can call in with 20 sec cooldowns if your ammunition income is high engouh, which it is with supply drops.