Harmlessness is not admirable.
Tough problems demand tough solutions, and tough solutions demand tough people.
You might object: wouldn't it be better to have no aggression in the first place?
Wouldn't the world be more peaceful if we all looked after each other, and avoided conflict, and only took what we needed? Wouldn't we be better served if we worked together, dividing the world's spoils evenly rather than competing?
Maybe.
But this would require a fundamental shift in human nature, at a level far below conscious action. Until we've figured out how to upload ourselves into flawless computers, there remains nuance.
And for as long as there's nuance, aggression is necessary to keep society from collapsing.
Assuming, of course, that it's properly integrated.