There is none.
The only reason why we should do it is "feels". Logically, there are no pros, there are only cons.
At best, the 'refugees' which are invariably a very solid majority young men are deserters, fleeing their homeland when it got tough. With that amount of morals and convictions, would you really want them as citizens in your nation, when they'd flee again when times got hard instead of working harder to fix it?
And at worst, they're active combatants, whether it's ISIS, one of the other various Islamic terrorist cells, or just waging cultural war by making America into West Pakistan.