One detail I loved about Star Trek VI is that Klingon blood was a light purple color. I liked it because it made them seem a bit more alien and otherwordly than before (as opposed to simply a recycled humanoid species just like us). I don't pretend to understand the chemistry of Klingon purple blood (as opposed to Vulcan and Earth-crustacean green blood from copper oxidation) but I thought it gave them a fun, extra alien touch. Yet in the newer incarnations of Trek, Klingon blood is as dark red as ours. What gives? Why would anyone involved in Trek want to reduce the alien novelties of their aliens?