You forgot about Sky Island, Water 7, Namis reaction to the war, fishman island, etc. Luffy and Nami are shown to have a much stronger connection with each other than any others in the crew, Zoro excluded. While I agree that Oda doesn't focus on Romance, I wouldn't put it past him to end the series with a timeskip with Nami looking out into the ocean holding Monkey D. Ace in her arms lol but I don't think we'd see how they'd get there.
Also, while Nami and Usopp have a lot of scenes together, they're always comedic. With Luffy, while a plethora of them are comedic, Luffy is the only person that she has scenes with on an emotional level. He is shown many times to be her emotional anchor, beyond that of just a friend.
You're right I don't know why but I thought those arcs happened before the Arc where Chopper joined, maybe the movie for that confused me because it had Robin in it..
The Nami/Luffy moments were pretty awesome, I miss the, everything from the way they met, to Arlong park, when he destroyed her office, to climbing up a cliff rock, with his bare hands with her on his back, to him saving her on Skypia to the speech Nami gave him when he was stuck between two buildings, were all epic monts. I think Nami's is the one Luffy has allowed to wear his hat, something that he hold dear to his heart, and she was the one who fixed it when it got damaged.
I miss that part of the manga, the current save a princess has gone on for a bit too long, we need more Nami and Luffy moments, though right now I would be happy just to know what Nami is up to.
Back to the topic in hand I don't think Kishi is a Sexist per sai, he has shown how he likes strong willed women, but you can't help but feel that he really had little or no contact with the opposite sex, everything he learnt about women he learnt from his old fashioned Grandmother or something. His views about how women love felt like something from a different century.
Also I don't think even he realised it, but the three women he showed who still had a career past 30 (Tsunade, Mei and Shizune) are all single unmarried women, all the mothers are stay at home mothers, none of them have a career, only person that did was Kushina in the RtN movie. This I find bazaar, I come from a traditional Indian, Muslim family and all three of my sisters have had a career after marriage.