Ok lets say they are just different. Tamura Sensei is the only one I've seen who looks similar to the old school shihan or O'sensei. I think this is because he was O'sensei's favourite uke (so I've been told) and that he started a little bit earlier than the most of the current Aikikai Shihan teaching in America and Europe.
I could guess that you don't think different is a bad thing. I think IT IS "further away" from O'sensei. Tamura Sensei is closer to O'sensei IMO. What happens if everyone keeps changing and becoming further away? See where I'm coming from?