Applause for taking the time to think through this, deliver the speech and share it here. I would argue however that the white culture you define is simply your definition. There have been people of color in this land for much longer than white people. The cultural norms came out of a set of moral ethics, codes or standards that survived and even drove the independance of this nation from the oppressions of England and as seen in history. There is dignity in compliance and wisdom in a respectful response.
I feel a more accurate portrait would be to say that there is a wise way to go about life and there is a reckless way. And, there are degrees of each with perfection in either direction being nearly impossible for anyone. Everyone finds themselves somewhere along that continuum between wise and reckless and likely even at different points in different areas of their life. In their work, they may be wise and with their responsibilities at home, they may be very wise but in their management of money they may be down right stupid or reckless.
When we are interacting with each other, regardless of the tone of our skin, we have an opportunity to be wise and respectful or to be reckless. If we argue or disagree then of course we and everyone on our side is going to pick at the other side to determine why they are so weird and do not see things our way. Easy attributes to pick out are sex, vocal tone, race, hair color, looks, style, mannerisms, etc.
A broader and more accurate view of what you are proposing is this that people disagree and when they do they often select things about their opponent that are easy to hang on to in order to potentially understand why there is a disagreement.
To use your example a woman has the same emotions or thoughts that a black person does when they are complaining about working conditions, seeking a raise, getting pulled over, etc. etc.
When I was in military bootcamp, I found that conformity, respect and meekness allowed me to exists under the radar of those in charge — those that had the ability to inflict pain in the form of push ups. So, it was a wise move for me to conform and it benefited me although somehow I did get on their radar after a few weeks.
If we attend a formal dinner then there is an expectation of how we are to prepare and present ourselves. Etiquette is an important aspect of interpersonal relationships. Ignoring those social graces just makes us look disrespectful, uncaring and selfish.
Our personal biases are best savored in the privacy of our own environments but when we choose to interact with the society around us then all of us are responsible to walk respectfully within certain framework. That walk may feel like a greater distance for some people and it very well may be but that does not mean that the established standards within a social setting should change just because it is a bit of work for someone to conform.
My sense is that this is the crux of how culture changes and shifts. With enough pressure, for example, for a long enough time that formal dining experiences should be loud and obnoxious then eventually they will become just that and those that are not comfortable with it will need to either enjoy being entertained by those that are or to stretch themselves to be more vocal.
Bottom line is that your argument is well delivered but simply does not zoom out to a wide enough view. Therefore, I argue that it simply adds fuel to an already eruptive fire without articulating a compelling or doable solution.