Having seen the three ascension paths, it occurred to me that not ever pop in an empire, nor even every empire itself, would want to pursue them. In every age and in ever population there have been those who resist progress for the sake of suspicion of the new and different. So what if every advancement was met with opposition from Reactionaries?
Perhaps they could make up a faction in one’s empire that had to be dealt with. One thought is that it would be stronger in fringe worlds, further from the persuasive power of the heavily populated core worlds, and grow with the pace of advancements.
If you go too far, too fast, then they might revolt.
You would be able to deal with them through a verity of methods, such as persuasion, expulsion, or violent repression. If the reactionaries win power, then they would start undoing your advancements or even spark a civil war. One step further would be to hint in the events that a similar movement undercut and ended the advancement of the Fallen Empires.
And finally, if an empire rejects all three paths, deciding to keep their clunky, error riddled biological forms and ignore their psionic potential, they’d go down a fourth path, that of Reaction. Not sure what the perks should be, since this is basically your empire rejecting all of the perks offered by the three paths and choosing to remain stuck in the past, so to speak.
Though once idea is unique options with Fallen Empires (?).
I don’t know, except that I want to do a play through as a bunch of stubborn luddites shouting at the ascending species to stay off their lawn.