I would honestly have a lot more sympathy for a Baathist group than ISIS. The USA has made fundamental Islam their very explicit enemy and as much I respect the rights of third world countries to self determine, theocracy is an unacceptable solution to the puzzle. If a government of the Kurds, Sunnis, and Shi'ites could agree that the US should butt out, then that would be an obvious solution.
From a realist point of view, no western nation will tolerate on the ground loses to ISIS, so we are restricted to an air campaign. This will be less effective, but at least we will protect those precious citizen lives. This will mostly likely not result in the anti-fundamentalist results that we hope for, but we are pretty clearly unwilling to commit more resources than an air campaign.
Edited to fix the spelling of Shi'ites.