For many centuries, the form of a building communicated its purpose and function. There was an explicit correspondence between its outer form and its original reason for its construction.
A church had recognizable features, including a cruciform plan, spire, dome. A typical museum or a library would be expected to have elements from traditional Greek or Roman architecture (columns, pediments etc ) showing the visitor civic grandeur.
However at the turn of the 20th Century, architects and philosophers including Adolf Loos, Ernst Bloch and Walter Benjamin were challenging the traditional view of architectural design by favoring abstraction over symbolism.
The upward expansion of New York skyscrapers at the turn of the century were challenging the traditional form that buildings took in their external appearance, These skyscrapers, that were being championed by the father of the skyscraper Louis Sullivan, were no longer a symbol of their meaning, they had a number of multiple meanings under one roof. Therefore the form of a building was no longer viewed as a literal communicative device for its original purpose. The traditional symbolic code of a buildings form was being challenged by modernist architects
The modernist movement gave architects the freedom to create forms for buildings without the traditional restraints of the past
In any industry, standardization is seen to cut costs and make production easier, this is no exception in architecture. Similar components are seen across different architectural projects using standardized materials and production methods
Inspiration for new projects can often take the form of architectural copying and pasting, there are many examples of this across many countries, often associated with an acknowledgment that a certain design success warrants repetition through other similar looking buildings,, which you could argue is the best form of flattery.
As an architect reaches a certain celebrity level, their practices can become known for certain styles, form and function, as an example, Frank Gehry's free form metallic layers, Norman Foster uses structural skeletons and Zaha Hadid's curving and architectural geometry. This can lead to the creation of buildings that the architect thinks the public and the client expects rather than how the building should be designed for its purpose and context.