Board Thread:Episode Discussions/@comment-1512913-20180906224733/@comment-31099706-20180911134035

Well, if you take a look back at the chapters during war, Orochimaru, Sasuke and Taka entered and left The Leaf just like that. Either it means the barrier holder has duties on war, or is dead, or is injured or it's just too complicated of a jutsu to hold without expecting sudden threats.

Yes, the Otsutsuki's attacked and they will definently attack again, hey the Leaf even wondered over the idea of this attack being responsible of  them, but they brushed it off on the basis that Sasuke didn't report any unusual things. So, I guess any Otsutsuki related threats are warned by Sasuke. There wasn't much point to the barrier since these guys can just fly atop it and jump or teleport to where they want to in the village. They literally just flew down in the middle of the Chunnin Exams, showing that there would be nothing near the level of what the Leaf presently has, to secure and alert them of these guys. The barrier is best for threats like War, suspicious sudden attacks(that has to be expected from the start) or strong enemies like the Akatsuki. Even then, Pain just flew in(by throwing himself) into the village, if someonewas running, then they could be handled right close to the walls, preventing them to enter any further.