Most people don't like gimmicks, that's why.
I don't know. Look at smoke pots. It's gimmicky, but it is a very good ability. It both gives you a way to smoke a front/mg or save a tank or you can use it to just gain intel on your opponent. The cheap cost also means that you'll never be in a situation where you will not be able to use it. So, gimmicky doesn't automatically make an ability not being used.
Otherwise they could just turn it into something like the "Assault and Hold" of the German Infantry commander. It's 70 munitions as well, global, increases capping and gives an nice offensive bonus that is worth getting sometimes even if you're not planning on capturing territory.
Or an entirely new ability, like
"Dig in"
US infantry in heavy cover and buildings is instructed to dig in. They receive a -10% (or something more appropriate) to their received accuracy and 10% to their rate of fire.
It could be a passive or an active ability like the Con hurrah for 20 munition for 20 seconds or so. Depending on how it is implemented the bonuses need to be different. A flat passive cannot be very strong.
Fits the urban theme perfectly.