I don't think you realize how close ISIS came to winning in the ME. If they had overtaken Baghdad and Damascus it would have been game over.
They were completely ruthless and ruled by total terror. This was a war every bit as important as WWII. They simply could not be allowed to take over. Assad is ruthless too, but mostly with those who try to overthrow him. In Damascus women walk around unveiled, they go to school and university. All religions are tolerated. All the Christians in Damascus support Assad. There was no freedom of religion in the part of Aleppo ruled for 4 years by our "moderate rebels".
For democracy to work, over 90% of people must agree to follow the rules. It will not work in Arab countries in the foreseeable future because of widespread sectarianism and tribalism.  The best Syria can hope for is a benign dictatorship.