The appeal of the constructor is that it can slow the enemy. It has already been severely nerfed by switching to the prefab system and depletable wood supply, but then having an uruk break through in 2 seconds cos he has an iron axe combined with the constructor not being able to patch it, cos if you carry wood now, you loose it, means that constructor became effectively useless in slowing down the enemy. This makes playing constructor on lower player numbers mostly just detrimental to the team, which is sad, cos I like playing constructor.