What would make a government to rebrand their traditional currencies just to edit some graphic designs with excessive amounts of money bills involved to execute such project that doe not mean to brings more values to the currency neither does it boost the economy level of the nation?
Can't that be a good strategy to eradicate black money and fight money launderers and other criminals hoarding money from illegal activities and other illicit works they do around the country? If the currency or the notes have been modified, people having cash will need to visit banks to get their funds exchanged and get the new notes, and those who don't do that within a specified date would lose value for the money they have.
When such things happen, people who have stored a lot of money through illegal businesses would barely be able to come out and exchange all their cash for the new ones because that would reveal what they have been doing and how much money they have been hiding.