Re: Aikido IS a practical contemporary martial art
Learning humility is learning ethics. Humility is an ethical virtue found in many, but not all, ethical belief systems. Confidence is somewhat ethically neutral as it has no real impact on what kind of behavior it will allow you to do that you would otherwise have coward away from. But it is usefull to ethical behavior, irrespective of the specific ethic followed.
Personnally I think you jiujitsu friends may be developing more ethics in their training than they think.