It is possible to elect yourself supreme leader, but you have to be really, really big – and have empire of huge cities all over the globe. If you run your SE right you can also likely have one or maybe two of the factions as natural allies, which will help. Just be prepared for some party pooper to say NO! Then you have to get out your guns again. Also, friendly factions must might vote for you even if they aren’t submissive or allied. You never know…
And yes, the game is inherently violent. When you look at the SE you see incompatibilities built in. After all, the factions are designed with different ideologies, which are manifest in a faction-specific level of aggression (aggressive, erratic, passive) and SE that the prefer and hate. In addition to this, the AI has its algorithms set so that #2 hates #1, #3 dislikes both #2 and #1, and the others are trying to find a Big Brother to suck up to and a weaker faction to beat the snot out of. This relative rivalry and the SE conflicts are a pretty good way to breed war.
SMAC isn’t really a war game, per say, but war is a means to an end. Even the most passive granola munching and Birkenstock wearing Gaian will have to break out the ammo eventually.