Did you know that karate is having a comeback in America? Tae kwon do and kung fu have been generally more popular, especially after the "Karate Kid" films waned in glory, but Lily Donaldson here represents the resurgence of the Ryukyu Kingdom's martial art. Naturally, brandished nipples are a must.
Maybe it was fine to cover your chest up and tie your gi with a fat belt back then, but nowadays, nobody takes you seriously as a fighter unless your nipples (and, if possible, the rest of your boobs) are clearly visible. We don't make the rules, we just love the results.