From an institutional perspective keys have one substantial drawback: you have no way of knowing how many copies exist and no (realistic) way to get people to return them. Since you can’t ‘revoke’ a metal key you end up either changing a lot of locks or putting up with the fact that you have very little sense of who or can’t make it through a given door unless you change the locks after every other-than-amicable departure.
The temptation to use the oh so readily available authentication logs for creepy surveillance is a serious downside; but being able to just remove a card from the database and call it a day beats calling the locksmith (and in some cases the people behind the rollout do want that delicious data; or to tie it in with payment for r meals and vending machines and copiers, or both).
There are also some University facilities that do tend to need greater security: bio or medical research that involves animals can paint a target on your back; and it’s not like Lincoln Labs stopped doing sensitive fed work after they wrapped up their initial air defense and radar research.
Dorms and common areas are a bigger problem because, obviously, you subject basically everyone to the security measures; but given how bad “oh, the expelled for rape guy? nah, we made sure that he returned a copy of his dorm key, we don’t know hoe he made it back in” goes, admin can be jumpy enough to do it anyway (though, given how easy it tends to be to circumvent widely deployed access control (since people get fed up with it and quickly start politely holding doors for one another, plus lost cards that aren’t reported and the like, only really works well with a more manageable number of people who understand and accept the objective of the security measures) that one is heavier on theater than utility).
I’m not sure if this motivated MIT; but when I was in college there was the other, deeply umsecret but hard to get anyone in authority to admit to, motive provided by the fact that the university was busily attempting to expand into neighboring areas of rather high poverty and crime(you adjust to sleeping through the more or less nightly sound of cop sirens going in and ambulance sirens heading back out toward the hospital on campus; plus medical helicopter traffic).
Concerned parents tended to be pretty fretful about the ‘use students as the shock troopers of gentrification’ strategy; so it was very visible which parts of campus were considered to already be pacified(greens/quads, minimal obstacles, buildings with entrances on all sides) and which parts were expansion (fences, entrances only on sides facing the core campus, ‘blue light’ police call kiosk things, and so on)
