Well I personally would like if any interstellar drives were very late game/very limited, as I really want to, say, start sending out Orion-type/nuclear-ion ships well before I achieve world dominance, fusion-powered ones when my domenance becomes clear, and officially declaring myself leader of my home planet and the ten nearby star systems, skipping any useless linear bits. Then I’d keep spreading and dominating my star system, until I finish up out in the Kupier belt, just as I develop FTL, and declare myself a K-2 nation, at the same time as I declare myself ruler of a thousand stars, a feat that is now sustainable, as FTL drives or even messages can crush rebellions in a way sub-luminal travel just doesn’t. My brand new FTL ship would beat the message telling rebels I had FTL and reconquest them. At this point I’d go into a cold war with the neighboring powers lasting centuries over my spiral arm. This sounds so much cooler than “only colonize habitable planets, never far from your colonies, get to ascension in a thousand years, never get more raw firepower than planet destruction.” With limited FTL war would be too ridiculously destructive and slow for nukes or even relativistic kill missiles or anti-matter to be considered war crimes or worthy of MAD. And people, being people, really like their war crimes, so they’d be “forced” to build pulsar or kugelblitz black hole based weapons, the former just erasing life from solar systems at a time, and the later being literally unblockable world killers. A world with little FTL is a far cooler one then with unrestricted FTL.