That is a very pretty picture which perfectly illustrates the problem with Modern architecture. Everything framed in that shot is "Modern"; the buildings are glass or at least large boxes and the streets are wide highways which funnel traffic through the Back Bay. The neighborhoods which surround this stretch are all 19th century walking places and have amazing character. Modern places like this stretch of Huntington were designed to be viewed from a passing car like silent monuments. They are beautiful from afar but to walk near them is dehumanizing.
On the outside, that is. I'm not sure if I would change the area if I could. In a smaller city this type of urban mall development might be normal but since this place (Prudential Mall-Copley Hotel complex) is unique in Boston I might try to keep it. There is something rather cool about walking off Boylston St into a fully covered space and making your way to Back Bay Station or the South End or the Christian Science Center.
But I guess that is also another failing of Modernism, the thought that the old city is something to be ignored. I remember coming up to Boston a couple of years ago for a conference at the Copley Hotel and while I was there I never had to go outside (I was staying at a friend's place in JP and the first step outside was at Stoney Brook). This architecture probably wouldn't be as loathed if it didn't try to turn it's back on the rest of the city.