Most space 4X games, however, feature exceedingly little system variation, the systems themselves often lack a compelling graphical representation, and, on top of that, you basically colonize everything in sight and build everything everywhere, robbing habitable planets of rarity and colonies themselves of any character.
I certainly can recall the layout of the Blorg space (and the galaxy at large) easily, and I'm not even the one playing, which says something about how memorable it is. I'm not fond of their LARPing, so I'm pretty sure it's not because I'm attached to the "story," I just find the layout (particularly the peculiar gaps between clusters, the empty western fringe, that migratory flock of space cows) to be interesting. Compared to SMAC's "here's a slightly less tilted plain in the same exact garish placenta pink color," it's quite a step forward. The Civ/BE maps are also mostly just an incoherent mess of features, it's not like they have an actual Dwarf Fortress style geological feature generation type thing going.
EDIT: I think Stellaris also manages a bit of trickery by representing systems as big maps that things can move and fight on, which makes it feel much bigger than it otherwise would feel, even if it makes almost no real impact on gameplay. MoO2 and its derivatives feel very claustrophobic to me.