[quote=Yog Sothoth]
still the reluctance to share culture hints that the factions have some form of xenophobia and that usually doesn't turn out good when it comes to alliances. regardless, my faction will still be pillaging and plundering planets. hell they don't mind people from other civilizations joining their crews because it means a little more freedom for those poor souls who have to live in those uptight civilizations with their self-righteous morality, my faction believes in taking what you want, when you want.
[/quote]

You're inventing reasons where they aren't there.

Our nations are insular communities because they are designed as self-contained units which can be plonked down like bubbles anywhere on the map. There are vast physical and bureaucratic distances separating everyone. If we'd designed our factions for a setting more like Star Wars, where everyone has assimilated more or less evenly, then you'd have an argument. But our species are concentrated in specific bubbles and regardless of outlook that precludes close cultural association; military and economic support is still perfectly feasible, but you're not going to be able to send an Alkay spy into Graal space.