Again, sad moments are not character development, its only development is a character ACTS on it.
For example, Zoro losing to mihawk made him realize how far away his dream was, thats when we start seeing Zoro actualy training instead of just lazying around the ship.
Zoro saying he would kill Luffy if he gets in the way of his dream when they first meet, then giving away his life in order to protect Luffy is also character development.