That is how at least I'd like it. All the other fields have a global config level DEFAULT option, but the pre-sim script does not. Adding ${DEFAULT_PRE-SEND_SCRIPT} in the pre-sim script field in a job (it should maybe be there by default), should execute a pre-sim script defined globally. It would make it much easier to run the same script on all the jobs.
An alternative could be to adds support for ${SCRIPT, script="my-default-script.groovy"}, which is fetched from the email-templates directory.
Or even better - both. Let the pre-sim script behave like all the other fields.
Are you wanting this at the global config level?