Given the current lack of diversity in our community, and that I have some (I will allow somewhat mysterious) sense that diverse perspectives will be useful to rationality, for example, in avoiding projecting our preferences, I personally believe that in a more diverse community we will be able to have a better discussion of the issues at hand which will be more truthful.

You seem to be confusing racial diversity with ideological diversity.

Edit: Since you seem to have misunderstood me let me clarify. Your argument about the benefits of diversity is about the benefits of ideological diversity, whereas your complaint is about the lack of racial diversity.