Kid was never really planned in the beginning (none of the Supernova were).
It was also only in the second half of Wano when he finally got a bit of development, but even then it wasn't much at all.
As much as I've criticized Oda during WCI and Wano, I much rather have him realize that he can't handle a boatload of supposedly "important" characters in the finale/big war (he has shown time and time again that he's bad at this) and trim some fat now than him just trying to write roles for every halfway meaningful character and create another dragged out mess in the end.