Only God knows the reason Nami's breasts have quadrupled in size throughout the series. I'm sure you've noticed, and for those who haven't, let me spell it out for you...
Here is a snapshot from Nami's first appearance.
Now... here is from the 93rd Episode. As you can see, Oda has doubled them in size at least.
And the final result...
Yeah... What are your opinions on this? Why have they changed so much? Not only that, they jiggle every time she SPEAKS.
Why would Oda increase their size so much.
(...Err... I sound perverted at this point, correct?)