Kiyani did not do it because of the following reasons:-
1- Bad relations with US.
2- Pressure of US to launch the operation which would have given an impression that PA is following the "orders" of US.
3- Political issues like memogate scandal.
4- Questionable prepadeness of troops and intel agencies for another large scale operation.If unprepared then time was needed to make them ready.
5- Lack of cooperation with Afghan govt.
6- Mistrust with US.
Kiyani's era was more tough as compared to Raheel Sharif. Morale of millitary was low, public support was lacking, popularity of TTP was high and large chunks of Pakistani territory were under TTP control at the time he assumed comand.
Let's not forget Swat operation under leadership of Kiyani and let's blame ground realities of that time instead of blaming Kiyani.