> Or maybe they need warriors, since their race has already collectively modified itself to delete wasteful things like aggressiveness and anger.

Highly doubtful. Any trait that's collectively exhibited was adaptive and such a spefies would value it to some extent, so they wouldn't breed it out entirely. If some new sub-species found a better way and outcompeted those with this trait, then they are already better adapted by definition, and so wouldn't need this trait.