When you see those old pictures, you’re seeing a small urban elite. The majority of most Middle Eastern countries was rural until the 1970’s, with some countries being rural majority until slightly later. Turkey, for instance, was rural majority until the 1980’s. Afghanistan is still rural majority today.
While some countries have gotten noticeably more conservative in public (Saudi Arabia and Iran, where legal changes since the 1970’s enforced particularly austere, but quite different, systems of rules, for example), most have generally gotten more permissive overall since the 1970’s on things like head-covering, dating, premarital sex. In many countries, Egypt, Turkey, and Lebanon notably, the old secular-oriented urban elite is still in place, still living life as before, but with massive urban growth, non-elites are much more visible. Istanbul was a city of one million in 1950 and is a city of at least 15 million today. This changes who gets seen by foreign journalist and, quite frankly, who is even considered important by elites in the ountry.
Much of the supposed liberalism of the 1970’s seems caught up in male fashions of the period. Male fashions were certainly deeply, deeply influenced by Western trends, as they continue to be today. I live in Istanbul, and there is a large stream of tourists from the Gulf. Men tend to wear something like t-shirt and cargo shorts, women in some form of abaya. People tend to look at old pictures and see Western clothes and automatically assume Western values. This is not necessarily the case.
I’ve never seen any real evidence that the Muslim Middle East was more liberal in the past; in fact, all the evidence I’ve seen points consistently in the opposite direction. The one caveat I would make are places like Saudi Arabia and Iran, which saw extensive changes in legal regimes in 1979. Saudi Arabia was never liberal and it’s not clear to me that Iran is, in terms of opinions held, actually less liberal today than it was in the 1970’s, though now there is an austere moral and sartorial code enforced by religious police which obviously changes the outward appearance of the country. But there is a thriving subversive underground, just outside the of state’s gaze—see Pardis Mahdavi’s Passionate Uprisings: Iran's Sexual Revolution or Janet Afary’s Sexual Politics in Modern Iran for more on that part.
For more, see the following two older posts I wrote—the first is particularly about what you’re interested in.
Could you define "liberal"? Depending on your definition, the answer varies quite a bit.
The Middle East is a vast area that, as it happens, does not include Afghanistan. Afghanistan is, geographically, historically, and culturally, more similar to Kyrgyzstan than Iraq.
But to answer your question, let's go back to the beginning. Well, not the entire beginning. Afghanistan as we know it began in 1747, but it gained its 'independence' (though it had never been directly administered) in 1920. This was partly because the King had led a program of modernization, centralization, and international outreach, which he continued. It was during this time Afghanistan really got rid of banditry and tribal raids, becoming basically peaceful. There was a conservative reaction to some of the more radical reforms in 1929, but within a year royal forces had re-established control and a more moderate royal was in control. He slowed reform and was assassinated for it.
With that death, Mohammad Zahir Shah became Emir. He continued the more moderate course. The Emir and his government repeatedly sought modernization while placating conservative elements, sometimes backing off, sometimes pushing forward as the political climate allowed. They notably stayed away from things like banning the burqa and other heavy fisted methods. By 1964, Afghanistan was a constitutional monarchy that was partly democratic, with a relatively modern capital city and open elections. Many of those pictures of women without headscarves talking about academic subjects are elite women from the capital. But you can see them interacting with women in burqas too. A sign of the monarchy's approach: the burqa was neither required nor forbidden.
In 1970, Afghanistan entered economic crisis. Then there was a two year drought through which the crisis continued. In 1973, a former politician led a coup, citing corruption. This was true, but it had always been true, and the coup was probably triggered by the monarchy's weakness and the dissatisfaction of pro-modernization factions. Regardless, the new government was rather dictatorial.
This was theoretically pro-modernization through single party rule. However, the modernization program gave way to pragmatic compromises to maintain control, and modernization stalled and even rolled back. The government was deeply unpopular and couldn't fulfill most of its promises. In 1978, the Communists launched a coup. The Communists too were not popularly supported and were highly dictatorial. In fact, they had less popular support and were more dictatorial. They quickly proclaimed state atheism and began to do things like ban beards and burqas and closed down many mosques. They killed (or tried to kill) leaders they suspected of being anti-communist, including basically all religious figures. This caused those in the center of the country to flee to the edges, and local powers to arm themselves and resist central authority.
This is the beginning of the warlordism we know Afghanistan for.
The Communists were never very popular and quickly had to call in Soviet support. The Soviets were not particularly capable of governing the country either. But as Communism is, broadly speaking, a leftist ideology, they emphasized the modernity of Communist Afghanistan. They portrayed all their opponents as backwards and reactionaries without major popular support. This is where the idea that Afghanistan was liberal in the '70's and '80's comes from, even though it was arguably safer and freer in the '60's under the monarchy. This view is still popular with people who see the monarchy's compromises with religious authorities as too soft handed.
This Civil War cum Anarchy continued throughout the eighties. The Soviets withdrew in 1989 and the Communist government fell in 1992. The various warlords met to discuss peace settlements. They actually did come up with an agreement, the Peshwar Accord. But an Islamist party, Hezb-e Islami, had not done particularly well in the settlement and started a war. Several warlord forces received support from foreign powers, resulting in a new civil war. Two years later, the Taliban emerged, explicitly with the mission of bringing peace by bringing Islam to Afghanistan and ending warlordism and corruption. (It didn't matter, of course, that Afghanistan was virtually all Islamic already.)
The Taliban were very successful for a variety of reasons and by 1996 controlled two thirds of Afghanistan. The northern third was controlled by warlords opposed to the government. The Taliban enacted their strict interpretation of Islamic law, which was rather horrific in many ways. This was immediately used as propaganda fodder and it squared rather nicely with the deposed Communist government's claims that it was the only thing keeping Afghanistan 'modern'. Its opponents had triumphed and now a very conservative, very reactionary, very brutal government had come to power. (Although, arguably, not any less brutal than the Soviets/Communists. But, naturally, Communists saw brutality against religious populations as less important than brutality against communist sympathizing populations like educated urban dwellers.)
TL;DR: The moderate modernizers suffered from a long economic depression, were ousted by a coup from more radical modernizers, who in turn were ousted by a coup from the Communists. The Communists were heavy handed radicals and started a civil war during which many (but not all) of their opponents were conservatives. These groups agreed to form a moderate government but far right Islamists launched a civil war before it could get off the ground. These Islamists were ousted by even more radical Islamists known as the Taliban. The Taliban proceeded to create a highly reactionary Afghanistan.
What is your source for this idea that the Middle East was liberal?