I think a quote mentioned in RTW went along the lines of:
"An Empire is not maintained through timidity."

I used to try the soft hand approach in my first campaign game as the Julii(unmodded of course). My reward? Frequent unrest and riots. The worst perpetrators of my settlements was Cordoba and a few of the cities in Asia Minor. I tried throwing games, increase the quality of life of the citizens, and for what? Riots against my garrissons, damaging government facilities... total chaos. I changed my style to the Iron Fist. Any revolts were dealt with mercilessly. Enslavement was too humane a treatment, I said "Crucify them all! I want a road filled with crucified rebels lined all the way from Cordoba to Rome!"

Seriously, kill the population. It's the best way to deal with revolts. Having a small, frontline-quality army in central areas is a nice way to deal with the nastier revolts. Your expelled Town Watches/Garrisson troops can combine with these Legionnaires and absolutely crush the Rebels.

Again, "An Empire is not maintained through timidity."