Propaganda hoax from who? The US seems to be looking for every reason possible not to attack Assad. There is also pretty convincing evidence for the reality of the attacks.
And while you 'would rather' Assad was in power, the Syrian people don't really agree with you. It already is a hell, Assad only controls part of the country and things won't get better till he has gone, even if they get worse first. It is a hell because of Assad and his desire to hold onto power by any means necessary. What do you think attracted all the foreign fighters there in the first place?
Also saying things were better under Ghadaffi or Hussein misses the point that most of the carnage is a direct result of 30+ years of living under a brutal tyrant. Repression cannot last forever, and when it blows up bad sh*t happens. But Ghaddaffi, Hussein, Assad weren't the ones preventing it from happening, he was the one causing the pressure to build. For example, It's not hard to identify causes of sectarian and tribal conflicts in Assad's Syria or Hussein's Iraq.
Supporting people who use chemical weapons on civilians, castrate, rape, torture and kill men, women and children, imprison hundreds of thousands of people deemed 'threats', enrich themselves at the expense of the people, rule through fear and violence and turn instruments of state into tools of oppression rather than protectors of justice in the name of 'stability' is what causes this to happen. It is naive and immoral short termism that ****s on normal people and their futures and treats them as incapable of enjoying the rights and responsibilities that the West takes for granted and would fight to the death to defend.
Support for Assad, however rationalised, is every bit as bad as support for ISIS.