Nami's character : An analysis

1. "She's useless"

Just because a character isn't actively fighting, does not mean they're useless. Nami is a navigator, and that was why she was recruited.
This being said navigators are easy to find, and countless people have made it to the new world, just like the SH.

Despite that, almost none of them have information on Raftel. Considering Nami has information on how to get there, it goes to show that only a genius like her can make use of said information.

Yes, Nami being a genius is canon. She has been recognized by multiple characters outside of the SH, and has saved the crew from sea disasters multiple times, by just predicting possible weather.

She also took the crew to Sky Island, which is another barely ever accessed location, and extremely dangerous to get to. Adding on, she is determined to reach whatever destination Luffy requires, as seen in Sky Island multiple times.

2. "She is money obsessed"

If you watched her backstory, you know how valuable money is to her. It was equal to life and freedom. This impression was set as a child, and affirmed everyday growing up. If she didn't have money, she would lose people she loved.

This concept exists at her very core, and just because Arlong was defeated, her very foundation isn't going to change. Money will continue to be of value, and she will go for it at every opportunity

She lost her 'mom' because they didn't have money, and she most definitely does not want to see that situation again with people she loves. She clearly cares for Luffy, and even refuses to see him disrespected

"She's just there for fan service because boobs"

Most female designs in One Piece are like Nami's. Even if we say that her boobs are unnatural, so what? She's still very important to the story, and if you can't see that, then the character went over your head.