Likely because sections of East Boston, Chelsea, Jeffries Point, etc are just as old or older than Boston's core area and thus have a less suburban approach to urban form.
This side entrance and façade remind me of the refurbished malls in Southern California like the Century City Westfield in LA. Its not bad looking, but it doesn't have a "transit station" ambiance.
Much of the early criticism of this building is how it would not match its surroundings and that is what it does best. I'm impressed by how it interacts with the roof lines of the adjacent buildings, especially how the roof line of the podium aligns with CAS next door. The red brise soleil of...
And the Wharf & Navy Yard areas -- DC's "South Boston Waterfront" if you will. If comparing, I think DC is the clear winner in creating a modern and engaging public realm.
And a nod to another library not far away in downtown Orlando (especially that sweeping interior staircase), designed by none other than "Harvard Five" John Johansen:
Orlando Public Library
Orlando Public Library - street view
D
DC metro area especially if you include Baltimore has a hundreds year history of rows whereas Boston doesn’t. That is likely the prevailing reason there is no precedent to build them in the Northeast - that and the extremely high price of land compared to the South where they can afford to...
There are certainly examples of where this works better, as you've noted with Yale. Vanderbilt, University of Richmond, Princeton also have recent examples.