Student loan debt

When banks got too big they made risky investments knowing that the government would covered their losses if investments went south. This is called a moral hazard. The same thing was part of the plan when certain states like California and Illinois ran up their pension debt feeling that before the state went broke the feds would come in and save the day. Some feel that student debt followed the same pattern with those in debt believing that the feds would help them. If the federal government does step in, will this encourage others to take on debt they cannot repay, things such as home mortgages or even car loans and credit card debt. Currently there is $1.6 trillion in student loan debt and $1 trillion in credit card debt. Should the government pay off this debt? What would be the justification of paying off one kind of debt and not others?