What if the duration of wards was reduced for each hit it takes?
Currently you either have enough players and/or attack speed to kill a ward when you see it placed in the short time its visible before becoming invisible. If you don't have enough of either then there is little point in trying to destroy a ward and the health bar of ward is essentially redundant.
Players should be rewarded for reacting quickly enough to damage a ward to punish players who carelessly, dangerously, or aggressively ward near the presence of the enemy and give ward health bar's a reason to matter.