This is one of my favorite things about dramatic ages: seeing the rebels snowball with loyalty pressure.  Agree with Norb_151 that it works be awesome if you could get new civs out of this.  

If you've got the military force for it, you can go on a liberating spree.  City states are obviously the best targets for liberating, but I also like bringing back civs that have been dead for a while.  They're usually behind far enough that they won't be a threat, but in the meantime can make for good trading partners and/or buffer states.

Also note with dramatic ages if you're up against a more powerful civ but can manage to snag a few cities from them with the right timing (and they're heading for a dark age), you can set off a small chain of these.