Which is fine as long as your end users are not implicitly forced to use your creation. So an artist creating a controversial sculpture is totally fine, nobody forces the recipient to consume their art. But buildings are different, they should be user-centric, not vanity-projects to boost your career.
They should, but they do not.
Whenever I see "should" in a sentence I think: why is this not how things are? What are the incentives? In this case: who is the person deciding what gets built? What are the consequences for being over budget? (Calatrava I am looking at you).
Again, it depends on why you are designing something. If your goal is to just stroke your ego then you probably aren't going to care about the end user.