I agree with what you have said. The matter of the fact is that Afghanistan will never give up its claim on Pakistan’s territory. That has been proved by its history since 1947. The only solution to this menace is an adjustment to the Durand line to create a more natural, viable, and defendable Pak-Afghan border.
We must not forget that Afghanistan was the last country to accept Pakistan as a free and sovereign state. However, Afghanistan’s rulers, be it the kings, presidents, or warlords like Taliban, have never missed any opportunity to occupy Pakistan’s territory by force, sometimes committing naked aggression by lashkars and other times by using terrorism. Afghanistan was always supported by anti-Pakistan states like the erstwhile USSR and India.
Pakistan’s active role in Afghanistan effectively started after Soviet’s 1979 invasion and occupation of Afghanistan. Since Soviets came into Afghanistan with dreams of reaching to warm waters of Arabian Sea, Pakistan was vulnerable to be the next victim of the Soviets. It's worth mentioning that the communism was then globally advancing while the western ‘imperialism’ was on the retreat after suffering defeat after defeat in Europe, Asia, Africa, and even in South America in 1960s and 70s. Pakistan firm stand against the Soviet occupation of Afghanistan and an effective launch of Afghan resistance/Jihad against the Soviet occupiers in Afghanistan was a pleasant surprise even for the west, especially Americans, who considered Afghanistan as the lost cause.
Almost similar scenario developed again in Afghanistan when Nato occupied that country after the Taliban leadership foolishly refused to handover OBL and his cohorts for the nine-eleven terrorist attacks in New York. The people of Afghanistan subsequently paid a heavy price with hundreds of thousand lives and vast death and destruction throughout the country.