I don’t know, but I don’t think complication will be the issue here. Unless you can make the developers understand why you think it is not possible to recreate the container with the new volumes by editing a compose file and running docker compose up -d or just bind mounting a folder which you can edit on the host to add more content, it is not likely they would implement it. As I said we have never needed it and I don’t know anyone who needed. It is not just about Docker. There is no container technology I know (besides the modified Docker on Synology) that has this feature. Containers are always recreated or we use bind mounted folders when otherwise it would require too many restarts / recreating containers.
So, if you found a use case that is good enough to implement a feature that allows you to add volumes without recreating the container, you could start big change in the container runtimes in general.