Pre-Time Skip One Piece was just Oda trying to find ways to take of Nami's shirt every arc.
And then Post-Time Skip her design was just not having a shirt at all.
Then he put her on cold clothes for Punk Hazard, but made Sanji take off her top.
Then on Dressrosa you have Robin using a really short dress and gets "raped" by the Tontattas.
And you think Oda holds bak on fan serivce?
If that wasn't enough, we still have the fucking movies.
Sure, it could be worse. But he is not really holding back.