Baen has a fair amount of hereditary aristocracy, and seems to have a deep philosophy that's quite 'in the blood' for military matters. But science fiction is generally a literature of change, rather than one big victory and happy ever after. Fantasy has more of a tendency towards stability, when we beat down this present menace we'll get back to the golden age when everything was better, and just dissolve into it neverchanging for several eons…
There's quite a nice lump of meritocracy in SF, and no real shortage of plutocracies, but it's generally accepted theocracies are bad, as they tend to damp out change. Still, the evil, all embracing bureaucracy seems to maintain its popularity over military authoritarianism as an antagonist.
But no-one seems to be attempting new, viable techniques of social organisation. It is clear even to me, a political near null spot, that democracy has faults - indeed, without considerable watering down is not viable at all for large masses of people. So why isn't SF throwing out alternatives, showing us possibilities for humans to live together differently, if necessary digging into older civilisations for different systems of organisation? Where are the Brave new Worlds, with brave new inhabitants? It's one of the functions of SF to point out potentials - and they all look bad, right now.