Pretty much as the title suggests, I will be posting my thoughts on motivations of the powers in my campaign here, and welcome input from others on any portion of the story.
So far I have tried my best to make no side "the good guy" as well as balance strengths and weaknesses of the factions. The Empire has plenty of people and real estate, but is mineral starved. The Federation has lots of minerals, but will be unable to make full use of them unless it can find more space to expand, additionally the Empire military is slightly larger than the Federation meaning if other options don't open up the Empire will consider striking for the outer planets, the Federation in turn knows this, and knows that if opportunities to expand don't turn up, it may need to consider a preemptive attack on the Empire to prevent defeat.
Both have seriously flawed leaders. This amused me because the game gave them to me, one is a bit crazy, the other is kinda an asshat.