Why not use this money to pay public servants more?
If you gave someone a raise but they were still deep in debt, the raise wouldn't be enough to cover the growing costs of having a large loan loom over your finances. In this case it would be more effective to pay off the loan if you value said worker keeping more of their money.
Plus not all public servants are facing debt, which means that the people with debt are going to gain less benefit from an overall raise.