For an expanded explanation of my opinion, please visit this thread: http://www.debate.org/forums/society/topic/68994/
Architecture represents a society as it currently is. In Medieval times, Gothic architecture was popular during a time when the European societies went through difficulties, and people often relied on the spiritual for guidance in life. Thus the Gothic architecture represents darkness and light; the darkness being their gray, shadowy appearance, and the light being the natural formations of the buildings, as well as the material used, stone. In the modern world, however, we see buildings of no symbolism whatsoever (on rare occasions, we might, however). They are boxy, without a natural formation (e.G., curvature), nor natural material (stone). They are plain-coloured, blank, and have no story to tell. In other words, they represent our dull, fast-paced, corporate-driven modern society, which has distracted the individual from the spiritual realm, and enslaved him to the material.
Modern architecture represents the worst of our modern society. Such soulless buildings are tragic for the humankind, and I would, at all costs, want to revert to the traditional setting. See Edinburgh in Scotland, for instance. Beauty at its best. Modern city, but traditional setting. You are not lost in corporate filth there.
The definition of gruesome according to the Merriam-Webster dictionary is "inspiring horror or repulsion; grisly." I don't think I have ever been horrified or repulsed by modern architecture, to be perfectly honest. Modern architecture is boring and uniform, yes, but I wouldn't go so far as to say that modern architecture is gruesome.
Now don't get me wrong, most architecture from the past looks far more pleasing to the eye than even some of the better bits of modern architecture. But there are still some rather nice looking places being built. Look at central London, you'll find quite a few modern buildings that still look great.