I agree and logged this as a feature request. There are some difficulties with getting this to work in medium trust web sites, since the obvious .NET class to use - FileSystemWatcher - only works in full trust. The workaround is to manually write code that monitors the file system, and at this point it is not known if this can be done efficiently for large numbers of directories and files.
Since it is not difficult to manually invoke a synch, it is fair to say there are quite a few other feature requests with higher priorities.
But thanks for the submission.
Roger Martin
Creator and Lead Developer of Gallery Server Pro