Absolutely fascinating.
The problem I have with PVing everything is that you don't also have 200k somewhere collecting returns of 5%. So while the true PV may be lower, you still will have that tax bill and nothing to pay it with. (try telling tuition committee you need to save 5k a year to pay your tax bomb in 25 years.)
If one is contemplating rapid repayment (or even what's termed regular repayment) vs. IBR or some other IDP it is proper to PV the values. Assuming you borrowed the $ for lawschool (no scholarships) and assuming you will pay it back, you DO have the money. This is most relevant when asking oneself "should i pay down debt ASAP or reduce my above the line and shoot for forgiveness." A dollar not spent on aggressively paying down loans IS a dollar you have for investment.
Sure an ideal view of the situation would take into account peoples inability to view current financial status in relation to some future status, people are really bad at that. But the fact of the matter is someone who aggressively pays down a graduate loan is very possibly costing themselves 10's or 100's of thousands in the future. And again, I only mean this to apply to certain "middle of the road" type earners, at least relative to the legal industry. If at any time you believe that you'll fall out of IBR and trigger normal payments by earning around 175-200k, this isn't the best path since the earlier years of IBR will cause you to pay more interest. And that person WILL earn more money in the long run. This is ideal for anyone hanging a shingle (or starting any small business) or someone who is partially financially secure already, or anyone who doesn't mind deferring compensation.
Next i'll introduce my Married Filing Separately module.