You're kidding, but he's practically an extra along with the rest of the Straw Hats except Luffy, Zoro and Sanji. Usopp had moments, but it's hard to call them "character development."
- An entire arc on east blue concentrated on him
- Multiple fight concentrated on his character evolution, more than most strawhats
- An entire character arc from beginning to end in Water Seven/Enies Lobby
I'm sorry if those feels shallow for you (they are not) but those are character arc and therefore character developments.
but many people don't like it.
Most people in the fanbase didn't understand the point on the arc.
I recommend this excellent video to really understand why whole cake was so amazing: (and this video forget a lot of things narratively)
(I know that there is another good video from another one, but I can't find it)
The character of Zoro revolves around the value of honor while Wano revolve around the themes of revenge and parent/child relationship. Zoro had his moment but it was not his place to act, he was not concerned.