Blitzkrieg said
Explain.
I'm really tired so sorry that this isn't the best response, but I'll try my best.
Under the Empire a large amount of Tamriel was bound by one power that ruled everyone. They all answered to the empire and the empire did a decent enough job controlling all of the provinces. When the Thalmor came they completely destroyed the Empire's claim to all of it's regions. Skyrim went into rebellion, Hammerfell broke off, the Empire lost the capital for a short time, the blades were exterminated and the Empire could do nothing to help Morrowind.
The Dunmer are now homeless vagrants, the Empire is in shambles, Hammerfell has left, Skyrim is in rebellion, and this is all with the promise that the Thalmor, at any moment, are going to come crashing back down upon the provinces to kil countless more.
They bring order in the manner that they kill a lot of people, but otherwise, they're creating a world crisis.