There's 2 things here:

The incubator that was Building 20 was is gone, as far as I know. Many many good things came out of it, some of which got very big, starting with the Research Lab For Electronics right after WWII (it was previously the main building for the "MIT Radiation Lab", i.e. a place to prototype and in some cases build small lots of RADARs). As of the '80s, some of its 3 phase ceiling busbars were still live, one of my favorite professor's coffepot ran straight off one.

That's a relatively subtle thing, but to the extent MIT becomes stolid and not doing new things, becomes more of a place run by consensus and the conventional wisdom, that would be an important thing to look at.

The second is of course the Stata Building. It will absolutely diminish the useful output of what's now CSAIL, if for no other reason than those who need to be able to work without distraction by and large won't be able to in the building. It's the sort of thing that can put a ceiling on the difficultly of projects people will be able to do, if they can't get into or stay long enough in flow.

Obviously people will work around this, using e.g. laptops in quiet places, but collaboration will then seriously suffer if past research on the subject is of any validity (e.g. > 30 feet? or a stairway makes a big difference).

I don't know if anyone was out to get them, it's just that a) people who had weird and very wrong ideas about how to do things, like the head of the LCS, who among many other things tried to physically enshrine a permanent disconnection between CS and AI, b) people who simply didn't give a shit about those who really were going to use it, and/or c) people who were grossly incompetent, were in charge of getting it designed and built, but not the actual "users".

And the screwups are legion. Tom Knight, #1 Lisp Machine designer back in the day and someone who did a lot of important stuff, now a "synthetic biologist" AKA into artificial life, asked for one thing, a floor that sloped to a drain. Which he didn't get. And I now notice as of 2008 he's doing this at a company he co-founded.

I suspect those two fact are not entirely coincidental. And potentially a grave loss to MIT, that part of the future just might not be done there, losing "The Godfather of Synthetic Biology" per Wikipedia is not a small thing.

And I have the tiniest window into CSAIL, and can speak freely about it (my one theoretically vulnerable source isn't really, and hasn't told me anything I can't repeat), there's I'm sure much much more to be told, and sifted through by historians or archaeologists of science someday.

6.001 is a rather different thing, after the dot.com crash, which resulted in a crash of EECS undergraduate enrollment, less than half after being 40% of the student body for decades, people panicked, those with an agenda against Scheme/LISP used the opening, but primarily, MIT decided an MIT EECS degree was going to be a fundamentally different thing.

That doesn't mean they're wrong, just that if you're looking a focus on the 6.001/SICP sort of thing, you might want to look elsewhere, like CMU I think. And maybe this was inevitable, a department like MIT's or UCB's is simply never going to be the same as a CS focused department that didn't grow out of an EE one. And Sussman at least always thought the 2 subjects were both of great importance and should be taught together, he himself just never figured out a way to really make that work, including at least one experimental one year long course covering both prior to the development of SICP and the 4 6.001-4 courses.