Are there really four victory conditions?

Well yeah, when you're totally dominating, it's easy to win by any method. But you can get a research victory while being weak in other areas, and maybe an influence victory when you wouldn't be able to win militarily. Diplomatic victory seems a lot harder in 1.3, so that is about the same as a military victory.

I have found myself several times where to go for a conquest victory would mean having to fight several allied races at once, which my economy (in those games) couldn't handle. So, I go for an influence victory or tech. Other times I get a bad placement on a map, so I ally with the strongest races, and get a diplo.

If you want to be really technical there is only one result of the four, winning. But the game is about building the empire that you want to build, and the victory options reflect that.

I've won two games where I never fired a shot, having victory options that allowed such a thing made it possible. I've had others where I've won by conquest, but my culture is only a fraction of the galaxy (gigantic maps with uncommon stars, tight clusters).

Most of the time my fleet isn't even that strong (as far as the AI is concerned). They often have far greater militaries, but since my ships are better I usually can wipe the floor with thiers (they just have 20x as amny as I do). Since I operate small, a war isn't always a viable option to me, even when I am leading the galaxy in research/production, etc. So I go for something else.

So really, I think that having the extra options greatly increases the replay value, and overall fun of the game.

You can also disable some of the victory conditions on the setup screen when starting a new game.