Oda has always been overtly exaggerated, not only in body proportions, but also narratively -a 20 month pregnancy, a 141 year old hag, an oversized dude surviving an entire hour in a boiling pot while also holding a platform with his also oversized 9 retainers-. A lot of characters can fit their own entire calves in their hands, or an entire human body in their mouths. Yet somehow boob size is problematic.

One Piece is a series which has been running for 20+ years, a lot of people have grown up with it, and as they have gotten older, they have come to recognize things like Sanji's perv vibe in thriller bark/wano, and the depiction of female body types detracts from the story for no good reason (especially if you compare bust sizes pre-timeskip/post-timeskip what does that add to the story?). It's a needless distraction to appeal to a shonen trope that should've died a very painful death a long time ago.

Can I ignore it, yes, would I like to have seen Nami and Robin do more than change their hair and grow 5 cup sizes after the time skip? Yes. Give Nami a Wattson like scar from all her playing with thunder for example.