It's possible to get good scores with other victories, but yes, it tends to lean toward domination/conquest.
I think the programmers are still trying to find the right formula to use for calculating score. One tactic I used with Civ and Civ II (and I'm sure others used this as well) was to build my spaceship, but I'd have such a large lead that I could wait as long as I wanted to launch it, and maximize my score.
Civ IV scoring prevents you from doing this, but then it ended up favoring the forms of victory that are easier to achieve early in the game.
Ideally, the next scoring system will adjust for the type of victory, so that it doesn't have to be domination/conquest that gets a high score, but also works it so that if you "milk the clock," you are penalized in your score.