The question should not be if Pakistan needs an army. The question should be: Does Pakistan need the self serving army it has right now?
Simply put, Pakistan's army is the worst thing that has happened to the country. They meddle in politics. They disrupt free enterprise. They make up imaginary battles. They fuel ethnic divide. They splurge on personal luxuries (cars, plots, servant). Pakistan's army is essentially a backyard bully with nothing better to do than push around Pakistan.
Pakistan needs an army, but the army needs to be accountable. The army we have today might have flashy toys to play with but it is nothing to be proud of.
Pakistani politicians are far worse - if they had done their jobs properly, the army wouldn't need to interfere every now & then.