There's two kinds of topics that (generally) are accepted by top officials as suitable dramatic themes for escapist works... under totalitarian regimes:
The choice of these subjects seems to be the result of a natural distillation from the removal of unfavorable topics in their cinema.
Once you remove the war, social problems, racial / religious conflict, I suppose all you're left with is class and gender. Pretty universal stuff for we 'civilized' humans.
In this way, a person living under an oppressive dictatorship could still access some semblance of their private, individual dreams and desires.
Experiences of young love, familial belonging, friendship, sexual energy, heroicness, exoticness, prosperity, escape, anger, outsiderness, mastery, terror, regret, nostalgia - these are deep authentic emotions that could be accessed by any audience member.
This is how a private emotional catharsis can be regularly reached in a dictatorship -
Through the excesses of "moral" escapism focused on class and/or gender.
If movies were not necessary under these regimes, they would not exist.
But they did. And they still do. Not only in abundance - it's a key strategy to their power.
Because they serve a real State purpose: As an escape for those who can't escape.
Movies, by assisting in numbing or calming the population to the true situation they're in, the dictator is thus able to rule unbothered. The people are docile, confused, distracted.
Every diffusion of populist rage a movie offers a dictatorship is another year they stay in power.
So for you fascists, subversives, or scholars that want to survive during World War 3: