I think expanding on space culture and shit is definitely in need of doing. Especially since Stellaris could use with some ideological subversive warfare. I mean, we got mind control satellites, but we can't use them offensively? Realistically the notion of interstellar warfare should be one where all reasonable statesmen/fungoids would look for alternative paths to victory, as a world where nuclear missiles are standard ammunition is not one you want to risk losing (if orbital bombardment actually did anything ffs). That we can't spend influence to influence and subvert rival pops to make them follow your ethos with Solarwood vidya games or something is a right travesty xD
Then you can have options to block out transmissions from other Empires (upsets xenophiles, don't get any bonuses from research deals) or keep transmissions open (upsets xenophobes, allows subversion but gives bonuses to research on tech from neighbouring speshhliens on tech you haven't researched). How sick would it be to plant psi-warriors for example, and have them mind control a planet into your Empire?
Also on an unrelated note, it is quite sad that you can't release feral xenomorphs onto a planet in some sort of biological atrocity that populates a planet with angry xenomorphs.
Fanatic Materialism + Military
The US has done a lot to gain access to strategic resources. The military is just one means of many to further the materialist goals. Capitalism Ho!
USA is probably fanatic individualist + materialist
Fanatic individualists have more ethic divergence and could allow for divergence into the paths of isolation, globalization, nationalism, pacifism, militiarism and such it has fluctuated with
+materialist cos money yo