Things certainly would have been different. Whether they would have been nicer is a different question. Everywhere the colonial powers deliberately put unfriendly tribes within the same borders on the divide and rule principle. Not just the middle east, where for example the Kurds are in 5 countries. We should really give them lots of help to gather up their separated parts in Iran, Syria and Iraq. Probably leave the PKK (Marxist/Leninist Kurds) in Turkey alone. In addition to the middle east, both east and west Africa have suffered from these divide and rule borders. For example, some of you may remember when Nigeria massacred the Ibo. Now the Christian Yoruba and Muslim Hausa are in a pickle with Boko Harram. Ruanda got unbelievably ugly with the Hutu Massacring the Tutsi. And on and on.
One solution I have thought of is to have commissions help these countries redistribute their boundaries, and declare their resources, especially the underground ones as a common property with fair rules of dividing resources among the newly formed nations. Middle east, east Africa, and west Africa are at least three areas where this could make sense.
That’d be the perfect solution, but I think they’d still fight each other.
The Kurds are an actual ethnic group, unlike the “Palestinians” — and unlike the latter, the Kurds should have a nation-state. Carving it out of Turkey, Iran, Iraq, Syria, and perhaps a corner of Jordan (at least) will take blunt force trauma and struggle. It should have been taken care of during the dissolution of the Ottoman Empire and eventual devolution of European holdings in the region where the Ottomans had been forced out. But it wasn’t.
Having a Kurdistan owing the US for current and continued existence would bring another island of stability to the region, and create a good neighbor and ally for Israel.