Answer:
Because more than just a building, an architectural structure is a human expression. So, it must reflect the conceptions, not only of the time but the author as well. When an architect is projecting a building, he must think about how the audience would look at it, and the feelings they will have. A good example is the Gothic cathedrals.
Step-by-step explanation:
Well, now let's see.
The architects who project for example the Notre Dame Cathedral were influenced by the art of their time (the Gothic, in this case). So, the structure they were rising should contain elements of this style, such as complex decoration, stained glass, statues ornamenting the entrance, the idea of reach the skies represented by the building's height, the flying buttress on the structures, and several other elements. And when people look at the final building, they will feel fear, respect, moderation and many other feelings. But these feelings were possible, ONLY because the architect thought about what he would put on the structure.