In most cases those on the 20 or 25 year plans(the majority of people) will have massive tax bills. So while they have a reduced payment for 20-25 years they will have a substantial tax bill due upon forgiveness. The govt at this point is using paye and ibr to stop the future hemorrhaging so they will atleast recover the bulk of the principle from most borrowers whereas they would likely get substantially less otherwise. That's not how ibr was originally intended to be used but that is the reality of the current situation.
The govt could do a lot on correcting the student loan problem going forward by simply not allowing student loans to be used at for profit schools. The bulk of the current problem is from students at worthless for profit institutions. While people point out people who get say liberal arts degrees as the problem, it's for profits and the overall college graduation rates that have made student loans a $1trillion problem. The majority of borrowers never complete a degree and for profit degrees are worthless and many times more expensive. Correcting what's already happened just isn't likely to happen without the taxpayers eating a lot of money. We need to pay to fix the current problem and address the issues that caused them so they don't happen again. Instead we are just throwing more fuel to the fire.
For profit borrowers are a small component of the SL population, at least from what I see on the FFELP side (and esp. the private loan side).
There are millions of borrowers on IBR/PAYE. The terms for IBR are worse but the President's plan will probably result in consolidation into FDL and application/approval into PAYE. This is the agreement among most sell side analysts and my own opinion also.
As far as the tax issue, the difference between the tax bill in the future and paying off the amount over the next 20 years anyway is huge. If you make $45k for the entire 20 year period (hopefully not), then that means your non-AGI gross income minus federal poverty rate is ~28k, so you pay $2.8k/yr, or ~233. Even if you account for inflation making wages go up, so will the poverty level amount.
Anybody above the average loan amount (~30k) will benefit form the PAYE. Naturally that benefit goes down with the taxable forgiveness, but the more people that join up, the more that will lobby for tax forgiveness.
The government can do a lot more by mandating what tuition amount they will pay for. Or mandating risk-sharing with the loans, or simply underwriting to degree.
The problem with IBR is that it's effectively an option-arm on a house. You get to borrow far more than you can actually afford to pay back in the hopes you get it forgiven, or you eventually make enough to pay it off. This is why I feel the idea is so repulsive. You aren't fixing the problem.
These fuckwits in Congress thing the problem is loans expense. The problem is principal balance. Principal balance is caused by tuition expense, not by interest expense. Under their utopia everybody could afford a $1mm house as long as the payment was "affordable", even if that $1mm house was in Compton because their own ineptitude and thoughtless Taxpayer bounty causes what should be a $100k house to cost $1mm.