Billing per hour and document generation

I have always been convinced that if firms start using document generation software, they will become more efficient and it will take less time for them to create documents.  Since they can not make as much money by the billable hour, they should start moving to a flat fee model.  They should start making more money because they are producing so many documents.  Here is an article that discusses this ideal:  http://ijlit.oxfordjournals.org/cgi/content/abstract/eal019v1