Nami maybe was left hand, or whatever important role she possesed, but only before time skip. Like idk how you could talk about her character, when she was just turned into fanservice doll, nothing more.
People already showed few examples:
1. Dress Rosa - she listened commands from Sanji;
2. WCI - we all saw how Nami slapped Sanji's face, but for what was that happening? Some people said that Sanji should bring appologize to Nami and Luffy and that never happened. No conclusions at all;
You know how recognize important character from filler one? Events that happened with filler character was never important to story, and that's Nami for ya, after time skip. Her fight with Cracker wasn't explaned, case she was not important. When she made Zeus and homies listen to her, it wasn't explaned, case she is not important. Also her fight with Ulti was skipped, interrupted and over in most stupid way case Nami right now is Filler Character.