I'm not sure why people are surprised and annoyed that the headquarters tries to maintain some level of control. Isn't that the role of a headquarters? Maybe the question should be, why are there no non-Japanese instructors on the Hombu staff given it's international role?
Is it racism? Is it an expectation that a sufficiently proficient foreigner should go back to his homeland to spread the word?
I think there are two basics that I'll briefly expand on:
1. Aikido originated and took root in Japan
2. Aikido hasn't been around long
It seems to me that the Japanese people simply got a sizable head start of sorts, so it's only natural that most or all the people at headquarters are Japanese. I believe in time, there will be people of other nationalities and ethnicities making decisions at headquarters. As for now, however, it seems normal to me.