Giving students from high income families a tuition discount likely won't change their decision to attend, hence price discrimination. To maximize charitable impact with respect to financial aid, it could be argued that instead the funding should go toward other schools so that these all-star, low-income undergrads have more opportunities closer to home.
[1] http://web.mit.edu/facts/tuition.html
[2] https://www.nytimes.com/interactive/projects/college-mobilit...
With this pledge, maybe MIT can bump up the free tuition level for those from families earning under $80,000 to $125,000 like at Stanford. The number is somewhat arbitrary and depends on the sliding window of tuition rate. After all for well-endowed, prestigious schools, tuition is unhinged from services received / amount of spending per student.
There are certainly people that are dissuaded from MIT for cost reasons, and money could be used to solve that problem.
But it is a combination of scarcity and quantity, interestingly.
By any measure that is per-student, Caltech grads for instance are far superior to the average MIT grad.
However, MIT has better name recognition and looks far better in stats like "number of publications in top journals" or "number of Nobel price winning alumni", just because it has five times as many researchers and pumps out five times as many alums every year. So the winning strategy is to get as big as possible - but only as long as the majority of your intake is still in the top half-percent of the bell curve...
That's a pretty broad statement. I can think of a number of measurements where MIT comes out ahead of Caltech - entrepreneurship (measured per-student) would be one particularly relevant to HN.
You seem to be implying that it's necessarily a bad thing, though.