Romans were upset by the emperor´s decision to create more coins because they needed more coins to buy the same amount of food as before.
Roman coin constituted a guaranteed and has widely recognized value that enabled an easy exchange of value which eventually boosted not only the commerce but also the technology development due to the fact that all classes were able to work to own coins to be spent on all manner of goods and services., Nevertheless, The fact that the emperor issued more coins meant that people needed more coins to buy the same amount of goods, so they got upset.