A. for the devices to always stay current (new devices have technologies and features that are energy-efficient and improve performance, with features that are not available on the older printers)

B. to show that you care about their business and that you represent the best company for the job

C. to get a bigger contract and win more money through better margins

D. to save time in the future (new devices don't need to be repaired or maintained as often as the old ones, and if they do break, there is a great opportunity for a transactional sale, as you now have a trusting relationship with the customer)