This is why taking anime too seriously is ridiculous.
Hating characters for doing bad things in anime is pointless IMO, what annoys me is if the author tries to justify it. Nami is a thief and a pirate, she's not a "good" person.
In a lot of cases, anime characters' flaws are what MAKE them interesting. Like Zoro getting lost. The fact than Nami has no problem beating up her Captain says a lot about her character, and has nothing to do with Oda promoting domestic violence.