Well, that a very "crappy" "feature"...
I'm always organizing my downloaded files into meaningful directories, so, even if I ran that command, some days later the newly created directories containing the new files won't be shared.
I guess I could create a cron job to stop amuled, run the command, and start amule again periodically, but that would be an extremely "crappy" fix too.
I seriously believe you should add a flag we could use before or after a line on shareddir.dat, someting like:
/path/to/directory1
recursive /path/to/directory2
directory1 would be shared non recursively and directory2 would be shared recursively, and scanned regularly (every hour or more often, perhaps a configurable parameter on aMule.conf