Straight to the point.
Currently if you sent troops to defend others village, it consume the village crop. and the troops will starting to die when the village running out of crops. It is something bad for troop owner if the village owner is bad at maintaining crop.
what if the reinforcing troop is automatically sent home instead of dying? or at leaat the troop owner can choose whether it will be automatically return home (all of them), or still defending while slowly dying one by one. as it is something crucial if the troop is returned home just before the attack impact.