I don't think Zoro was "neglected".
He got the "scarring Kaido" moment.
He got the "cutting the dragon in the air" moment with a panel mimicking that Wanted one.
He learned that his village was founded by Wano people.
He had his nice moment with the people from Ebisu town.
He had the most interaction with the arc's princess from the SH's.
Some may say that he getting a new sword is a plus. I hate Enma, so, personally, I think that's a negative, but meh. Since I believe he's gonna either turn all 3 swords black at the same time, since he's a 3-sword user, or just Wado, it made sense to remove his black blade and give him another non-black blade. I just wish it was Nidai.
He participated on the rooftop battle.
I think there's a good mix of "battle" and "non battle" things for Zoro this arc. I just think people misplaced some expectations, thinking Oda would turn this into some other shounen where not always the MC is the one who solves the big baddie problem.
I had expected Zoro to take on either Doffy or Fujitora in Dressrosa, while Luffy was busy with the tournament thing. Didn't happen.
I expected Sanji to fight Katakuri. Didn't happen.
All Luffy.
I expected Zoro to fight some major antagonist samurai in Wano, didn't happen.
Orochi? clown.
Kyoshiro? Actually a good guy.
Kaido's secret son that have some twist sense of imitating Oden fighting like a samurai but it's still evil? Nope. Nice woman and might even join the gang.
Had to take some magical senzu bean just to go back to the original plan of Zoro vs King and Sanji vs Queen.
It's always been Luffy's show. I just think some people grew tired of it.
Giving Luffy two major fights in WCI while the "other mc" for the arc got nothing? That should have been the final nail in the coffin for people to understand that there's almost no room for other characters to shine. other characters get "moments" and that's it.