>>>Up to the First Gulf War, while he was a bad guy, he served as a buffer against the Iranians.<<<
Not only he was a buffer against Iranians, he was also a buffer against Sunni radicals, known as Al-Qaeda and Muslim Brotherhood.
The latter was probably a real reason of the Gulf War. Religious Arabs couldn’t stand it and joined their efforts to suck US into it.
It short, Saddam was a model secular dictator aimed to behead islamists of all colors.
Assad is similar in many ways but he is not in the same league. He also depends on Iranians for survival and for that reason only useful against Sunni terrorists, not the Shia ones.
Much of US foreign policy in recent years is working towards restoring the caliphate that was abolished in 1924.