You don't need to use the SAT or ACT as a criterion. The problem if you don't is probably two-fold.

1.) You're throwing out a signal that has proven to be pretty reliable in at least establishing a floor as what students have a good chance of succeeding and

2.) As a related matter, it's a very simple, quantitative, standardized metric (with decent predictive power) that lets you bucket applicants pretty easily.

Do you maybe throw out some applicants who are really bad at standardized tests, but would otherwise thrive in an undergraduate academic setting? Probably. But the data suggests that standardized testing is a pretty good predictor of success in school (which, of course, is not necessarily the same as success in life).

Potential directions of thought: Offer a series low cost test pilot class which allows potential students to take a single test course at MIT. The professors double as recruiters, they get to see them thinking.