A very valid question, we had militaty advantage but lost due to failed non military tactics. The initial claim of mujahideen should not have been made. It seemed we hurried on the plan, china was also not on board.
Pakistan should have made a better plan, mostly political one. An incident in siachen should have been made hot and few months later take kargil with excuse of safety in siachen. Pakistani claim on siachen is most solid among others. A good political and military front together was required for victory and its consolidation.
I still blame army as they should not have gone through with the operation without political plan and will. A kargil type operation would have made more sense these days.