That also brings it in line with the PHB and “standard D&D economics,” where 10 of one coin are worth 1 of the next higher unit. In the ARP rule set, which most intro modules were originally written for, it’s not 10 to 1 but 100 to 1.
I am guessing the primer initially carried over the ARP conversion rates (FYI, ARP is on the silver system & 100 silver makes a gold there) but that the campaign setting harmonized the economics with traditional 5e settings. Or PCI might of had to make the change based on the licensing agreements. Or something else entirely.
If you are counting your wealth in gp in 5e, then it should not matter much how you organize the currency.
