Just as contributions to retirement accounts are allowed with pre-tax income, so to should student loan payments be.
With interest rates on student loans as high as nearly 8%, taxing income before payment causes the effective interest rate to rise to nearly 11-12%. While this would be usurious if done in the private sector, the government does it to those that have invested in their own educations in an attempt to help better society.
Allowing individuals to set aside 10-20% of their income with a cap of $20,000-$40,000 would allow young Americans to get out from underneath the mountain of education debt that has piled up much sooner. This would allow more money to be pushed into the economy by these individuals much sooner and boost economic growth in the long run.