I would like to throw my support behind this request,  I have been using Scott's process of editing the XML, which is getting me by for now for transferring.

I would also like to add a similiar situation I ran into will lookup rules being removed that caused me problems,   I modified a stored procedure and added another parameter to the stored procedure,   I set the parameter to have a default value so it would not affect my other processes and applications that use the procedure.   When i refreshed the datasource in the forms administration,   it removed the lookup rule from about 10 processes automatically.    

Fortunately I was doing this in a dev environment so it did not cause me any major problems just a lot of lost work time to fix the affected processes.   

If this would have happened in production,  it would have created major problems and delays with internal users and public users making requests while they waited for me to fix all the forms.   

It would be very beneficial as Ege requested anytime an existing lookup rule is invalid during import or change in database,  disable it instead of delete.   Much easier to fix then recreate,  especially as the number of fields and/or processes is affected.