Arrogance is right up there with murder because it takes away someone else’s self esteem. I might be exaggerating, but seriously I can't think of anything else that is as detrimental to another human being. I think many of us are guilty of being arrogant once or twice (I know I have been guilty of arrogance much more than that), and it has been hurtful to those around me.
My mother taught each of us to be humble (so much so that for many years I could not take a compliment nor could I extol my skills or achievements in a resume for fear of being arrogant). However, like everything else one needs to define certain terms. Arrogance is not in moderation. It's not just acknowledging one's good characteristics or skills, it's going overboard to the point where one thinks he/she is better than everyone else and that he/she has all the answers. Humility places boundaries - it brings one back to moderation and always allows the other person to feel equal.