I do not deny this.
However, it is important to focus on the big picture. Nuclear strikes on Pakistan would certainly destroy the country but they will also indirectly damage neighbouring countries.
USA war-gamed a very limited scale nuclear strike on Iran involving a single thermonuclear weapon. According to the results, military objective was accomplished but the fallout on neighbouring countries was the real concern. And I am talking about just a single thermonuclear weapon.
Here;
For example, the new nuclear earth penetrator that the United States plans to research would use a 1.2-megaton weapon. According to a simulation using software developed for the Pentagon, if one of these weapons were used against the underground nuclear facility in Esfahan, Iran, 3 million people would be killed by radiation within 2 weeks of the explosion, and 35 million people in Afghanistan, Pakistan and India would be exposed to increased levels of cancer-causing radiation.
While you can decide the fate of a nation, you cannot control nuclear fallout. Simple.
Perhaps this study is fear-mongering too:
A nuclear clash could starve the world - CNN.com
People should learn to differentiate between the devastating consequences of global nuclear conflict and natural events of limited scale.