I have long been thinking that the openly aggressive approach some display in promoting atheism / political ideas / whatever seems counterproductive, and more likely to make the other people not listen than it is to make them listen.

I believe aggressive debates are not about convincing the people you are debating with, that is likely to be impossible. Instead it is about convincing third parties who have not yet made up their mind. For that purpose it might be better to take an overly extreme position and to attack your opponents as much as possible.