Tried playing Spore again 12 years later. The game really does fall off hard after the creature stage, I had a lot of fun building up my little guy but after getting through the slog of the civilisation stage I was too mentally fatigued to continue and probably won't pick it back up.
A Gamespot review from the time puts it pretty well:
Because the tools used to create and revise this creature are so robust and amusing, and each creation's charms are so irresistible, it's hard not to get attached to your digital alter ego. On the other hand, this intimacy is abandoned in the long, later portions of the game, when you lead your full-grown civilization in its quest for universal domination.
I think it would have probably been better if it reined in the scope and focused on creating a more complicated version of the creature mode. Changing your creature could have been more tied to actual selection pressure rather than unlocking new hands that you buy with "DNA points", socialising and fighting with other creatures could have been more involved than just pressing one of 4 buttons at the appropriate time, maybe they could have the possibility of the brain developing in different ways rather than just "you're smarter now, your pack size increases by one (1)"
Still made a cute little fella though
Buildings and spaceship