To argue this, we should look mainly at the fact that the conflict has now been going on for 30 or 40 more years and that various events have hardened attitudes on both sides.
In the late 1970s, there was reason for optimism with the Camp David Accords. However, there have been many very negative events since then. The Intifadas and the Israeli occupation of Gaza are two of these. The continuing Israeli settlement in the West Bank is as well. In addition, the 9/11 attacks and the subsequent "war on terror" that is being conducted by the US and its allies (Israel among them) have helped to heighten tensions between the Muslim world and the West. You could also mention the Arab Spring and the fall of authoritarian Arab governments that were relatively pro-Israel when compared to the popular opinion among their people.
All of these sorts of events and conditions have helped to create a situation in which a solution to this dispute would be even harder to find than it would have been in the decades you mention.