So?
The Romans did as much for the Greeks, when the Romans occupied all Greek territories. Not only did the Romans didn't force the Greeks to speak their languages or adopt their religions, it was actually the other way around. The Romans adopted Greek religion, especially the pantheon of Greek deities. And in between the 2nd century BC and 1st century AD, many Romans, especially the elites, learned how to speak Greek. Early Latin (2nd century BC) were not a great language at the time, so many were tutored to speak Greek.
Many of the Roman arts (like sculpture) were actually done by Greek artists.
But Greece was lands with old civilisations, and didn't need that much improvements as cultural centres because they were culturally advanced than the Romans, but the Romans did improve other lands they conquered, especially in the west. Cities and towns began popping up everywhere, and there were prosperity in many of these places. They provide more advanced education, built roads to aid trades and travels, built aqueducts and sewerage systems for towns and cities, better irrigation systems for farming.
Many lands kept their own languages and religions too. But in the western empire before the Romans came, the people were largely illiterate, so the Roman gave many of these languages with writing system, the Latin alphabets that would be adapted with their own languages and used widely in the western part of the empire.
Every past empires had offer benefits to the people they have conquered, not just the Islamic ones. But with every benefits there are negative trade off.
If you are serious that everyone benefit from the Islamic empire, then why didn't the Islamic Ottoman Turks return the city of Istanbul back to the Greeks? After all, Istanbul was originally a Greek city, called Byzantion. Byzantion had gone through name changes, like Constantinople and Byzantium, but it was still a Greek city even when it became Romanisatized. And it remained Greek until the Turks took it in the mid-15th century.
And the island of Cyprus have been decades issue of contention between the Greeks and Turks. In fact, the Turks were invaders, because what is now known as Anatolian Turkey had never been their original home. The Ottoman Turks, along with other Turkic people had originally come from Central Asia. The first Turkic speaking people to reach Europe were the Huns in the 5th century.
In any case, I think you probably know more about Ottoman Empire than I do.