One problem I have not heard being brought up at all is the customization system, so my issue with it is
if I buy a decal or a symbol for a tank I can only use it once and only with that one tank/plane (very annoying)
I think if the devs make it possible to use the decal twice and make it available for all vehicles of that nation it would really incentivize (in my opinion) more people to customize their vehicles.