Islam is whole social economic and political system it is not just limited to Prayers Fasting and Hajj its a whole way of life which included how to run governments what laws to make how to run economy
So why is a political/administrative system being imposed on the whole nation? There are several political parties, people can follow any one of them. It is basically like choice of voting. What is the exigency that this particular political system needs to be imposed over everyone in Pakistan who may support Islam as a political system or not? People can have the choice of voting and also the choice of religion then! Will that not be better?