It has only been signed because Ashraf Ghani is under lot of pressure from Pakistan after Peshawar.Considering no one else in the government was consulted, when the agreement was being drafted..shows there is no inherent strength to it...Even Abdullah Abdullah, who will be the next president, is asking for the agreement to be redrafted.
They also know, how Pakistan still continues to harbour most of Quetta Shura...and for the time being, they need Pakistan to get them on the table.
It will be like Pak-USA strategic partnership agreement, even though both sides hate each other, and continue to work against each other interests..a poker face is presented to the world.