The victory conditions are there if you want them. I leave them turned on personally. You never know how this game will turn out, but usually by the time you have air supremacy, it is over. I was playing an immense galaxy with 9 opponents last week (Crippling level). The Jayded Knife (forget the spelling sorry) showed up and took the 72 best planets and all the techs. (One of the more annoying events) They are not aggressive, but their planets full of soldiers with the best techs are beyond annoying. At this point of the game, all of my opponents were immobilized, but the planets were scattered everywhere (100s of my ships going everywhere really slows the game down). Influence victory would not work (because of the Minor Race), so I simply did the tech victory.
If you want a conquest victory, go to war with someone. Influence victory takes 10 turns and will be canceled if war is declared. Alliance victory is easily avoided if you don't want it.
To me, the fun of this game is a close match between you and the AI. When the outcome is obvious, I am ready to move on.
