While there is some truth to mass tourism can have negative effects but as you suggest what is the alternative? Roads ruin the environment. Cars cause C02 emissions. Electricity generation pollutes the air. Airflights create noise pollution etc etc. Let's all go live in caves !
One of the best things about tourism that all the urban, well off talking heads, well fed, that bitch and moan ignore is tourists introduce dollars into the poor regions of the country and provide jobs that lifts many families out of poverty. Whilst this might not matter to urban middle class [the type who complain] living in cities like Karachi, Lahore etc but tourism is crucial in parts of Gilgit-Baltistan and would be the most effective way to bring jobs in backward parts of K-Pk. Nobody is going to open a steel plant or a garment factory in Swat or Chitral or Hunza. In these regions tourism industry could lift entire regions out of poverty.