Breaking the will of the ego.
There is a fundamental requirement in spiritual pursuit that involves surrendering ones will. As long as there is repository of self-will that won't give up control there can't be an opening to something new. For example, if in the dojo we bring our own rules of conduct (whether religious injunctions, cultural and social norms, or personal preferences) we set ourselves in opposition to the prevailing standard. We impose our ways above the ones that are common to the dojo.
Many teachers allow this and see no imposition on their authority. But I would contend it because if our dojo is a place where we train in a spiritual discipline (as O Sensei would point out) then it is of utmost importance that we come to understand that the dojo is a sacred room where subduing our ego is the main aim of our practice. Without it we will never have to confront the strongholds in our belief structure. Upholding a set of rules in a religious context that where set in place in order to facilitate ego-death and self-surrender can not be used as the very reason not to obey dojo etiquette. Can you see how it contradicts the very essence of spiritual pursuit?
That's why it has been said that the back of the ego has to be broken. So it looses its tenacity to always have the last word. Once broken, or given up, it no longer serves as a justification for following ones owns rules. Spiritual freedom implies much more than rigid adherence to form, structure and tradition. True freedom lies in understanding surrender of ones owns mind. In the end even religious injunctions must be given up if the goal is absolute surrender to God, or truth if you prefer.
Dojo etiquette is there to facilitate self surrender: Be on time, be clean, behave, bow. So if this rubs you the wrong way it serves its purpose. The dojo is not less sacred than the church or the mosque so we can't allow ourselves to view it that way when it comes to our attitude. In foreign lands we are strangers and guests, so it's good form to humble ourselves and learn the ways of the hosts. This is itself self-surrender; not for your self but for the other.
Breaking the will of the ego will never be an acceptable practice to the ego. Self-surrender means letting go of fixed ideas, even good ones. It is my role as a teacher to point out these personal strongholds until they are all surrendered and given up. This is Aikido discipline. It is deeply spiritual.