how can anyone compare Hong Kong and Chicago to Boston? They are entirely different...as NM88 said
Boston needs to develop along the lines of it's own strengths...which is not and never will or should be a dominant skyscraper array
looking at the Boston Harbor picture the glaring blotch is imo the Harbor Towers... their only negative visual impact is from that dead on water shot...or from a view facing the water
if you stick a 40 story building where the garage is and; it will block out numerous buildings from different angles...for some of them it doesn't matter but others it would negatively impact previously nice views imo....
Not to mention the effect on the Greenway, which I don't think in itself suffers from being too wide...what it suffers from is a monocromatic background that makes the green lose a sense of density....what it needs is more sidewalk activity/ ground level density, night lights and contrasting colors along the route...height itself provides no positive benefit especially since that building would stick out from numerous angles like a middle finger out of a fist...it would be better to keep the Green Way streamlined with a fairly uniform height than to plop a dramatic tower place in the middle so chaotically.
I think that a tall building would only help is if it is something very sleak, curved and is cast with a glass tint that easily blends with the sky...another angular building wont benefit the area at all...so I also dunno why, unless you believe that the developer would contract some celebrity firm to design the building, you post pictures of the type of skyscrapers that would probably not go there...
I really wanna see the design