Some times the bone order is not ideal or the model has too many/unnecessary joints. Some might want to simplify the joints for games or prep a version of it for sale etc.

Often after creating an experimental character externally I'd import into CC4 and examine functionality with animation but then discover an issue that would have to require changes and unfortunately would have to restart the project all over again because CC4 doesn't have tools built in or an option like GoZ to send to another program to make an update and send back. akeytsu is free, I've suggested that a GoZ like bridge should be made so users could send it over quickly to add or remove bones and update it in CC4 but it probably would be better if CC4 had these tools built in.