You say this as though the Athletic Dept was doing this out of the kindness of its heart and not due to market-based forces that still left lots and lots and lots and lots of empty seats at most games, even after tarping off three sections.
I've always bought season tickets and donated even though I could get most of my tickets from the secondary market for literally 90% less in most cases, and I've done this for 20 years. It's honestly been my way of supporting the program even though they were usually cheaper ways to get to games (I'm not a management consultant, lawyer, or mega used car salesman).
If NU is just going to turn this into a business relationship where maximization of revenue on ticket sales is paramount, then the only way Northwestern wins the long game is if they transform into a dynasty program and supplants the Bears as the city's favorite football team. Otherwise juicing the market in the short-term is gonna be pretty bad for business.
...but I'd also like to think that shrinking the new stadium to 35K was a deliberate move to make the building purple (since in any given season you could count on the Iowas, Wisconsins, Michigans, Ohio States, and Nebraskas adding a solid 10-15K to the head count in Evanston.) Shrug.