Actually, removing or undermining those brutal dictators (like Hussein or Assad) caused all the bloodshed we see today. That same bloodshed everybody is running from... towards Europe.
Killing Gaddafi in Libya removed a big chunk of the Northern African barrier that kept the masses from running. Stabilizing the region would take another ground war, and then installing new dictators to keep the ISIS stuff from repeating itself.
So yeah, thanks USA. Let's hope whoever comes to it's helm next will try to fix this mess.