Actually .... i can imagine a scenario where Guest above, is running an FTP site or some constantly music collection growing mechanism and she would like to automate the process of deleting any incoming music that is say more then 90% similar with any already existing and 'approved' file.
Just thinking out loud.
But to be honest ; i don't think that very many users of Similarity would be trying to script this kind of automation - so batch mode will probably never get implemented as the current implementation is definitely a GUI based application.
S
PS. Usually software evolves from text/batch mode into GUI .... seldom the other way around.