As with other words like "frankness" and "ambition," some people use it to mean the right amount, applied appropriately, and other people use it to mean too muc

As with other words like "frankness" and "ambition," some people use it to mean the right amount, applied appropriately, and other people use it to mean too much, abused. I agree with what you say about the dangers of assertiveness, but I think the picture also has to include the problems caused by lack of assertiveness. People who lack assertiveness often think it's only their problem, but it creates problems for the people around them, too. Their boss has to worry that they'll end up working on the wrong things and that the problems they discover won't get the proper attention. Their friends and family have to put in special effort to figure out how they really feel about things, and they have to partially mute their own personalities to avoid steamrolling them. There is an ideal amount of assertiveness in every situation, often difficult to get exactly right, which is why it can be seen as a virtue.