The problem is that all you can do is paint the map and pacifists aren't good for that. Every ethos should be able to "win" the game, that's why we need victory conditions.
Victory conditions don't help painting the map being the only endgame. That's an entirely different issue, namely with the lack of non-territorial, non-military expansion/progression choices.
Right now, regardless of what the player wants, territorial expansion is the only choice.
Want to economically dominate the galaxy? -> Conquer more planets, built resource production
Want to reach the pinnacle of scientific development? -> Conquer more planets, build labs
Want to build the most powerful fleet in the galaxy? -> Conquer more planets, build spaceports
Without actually having interesting gameplay to tie victory conditions into, having them wouldn't make a difference.