No it isn't.
The way I see it, the shell of the garage is temporary. We're almost oversaturated with labs, so all it has to do is hold out long enough for the lab replacement to no longer make sense. Preferably it would turn back into more housing, split across 2 buildings, with some permeability between them. The lab will not only become a permanent barrier, (blocking the money view of State Street among other things) but will visually throw off the entire scale of downtown.
Once the downtown labs cat is out of the bag, the character of the entire city is going to be ruined. I always thought of late 20th and early 21st century Boston as a city of juxtapositions. You look down beautiful dense old-world neighborhoods, that often have skyscrapers framed at the end of the view. Instead all the views are going to become dead-zone walls. It's like if a museum had the world's most beautiful painting, but then put up a brick wall directly in front of it and told everybody to just imagine it was still there.
Since this is Boston, aesthetics SHOULD matter. Those who only care about utilitarian uses should move to any of the other cities that don't possess Boston's historical fabric and quirky juxtapositions. Labs downtown are basically this generation's Hurley buildings, city hall, etc except that they aren't simultaneously destroying existing neighborhoods. But the structures, which we rail against today, are going to be comparable travesties and permanent blights on the cityscape. In this case, we're replacing one terrible barrier with an even larger terrible barrier that's turned at a 90 degree angle to the original.