A point Harry Harrison made in just about every book he wrote (notably the Stainless Steel Rat series and especially the Deathworld trilogy) is that interstellar warfare is a null concept. The resources necessary are too vast and the plunder possible is too limited to bother. David Brin, when he writes "malevolent aliens" does not write of conquerers, he writes of assassins extinguishing whole species long distance as an afterthought.
Personal biases against hard sci-fi aside, this is a very interesting train of thought.
Edit: Also, I think I might be one of these jerks.