Oh yes, a dictator definitely needs to ensure that the people are afraid - of the secret police, of the next country over, of people within their own country who seem different and therefore vaguely threatening... Fear can feed back into hope, too; one thing people can hope for is "maybe someday we won't have to be this afraid."

Plus, of course, when people are eyeing each other in mutual hostility, convinced that the other group is just waiting to steal their things and their privileges and everything else they can lay their hands on, they're definitely not banding together to rebel. President Snow could do a lot more with the ethnic differences between the Districts; all that potential animosity is just going to waste right now.

He never should have let the Districts see each other as potential allies. That, just as much as his fixation on Katniss Everdeen, was his big mistake.