A good wall, as you call it, is a matter of its physical relationship to people and the way it can create space around us, a system of spatial relationship. It is very basic, but something that people, including architects, often forget.
If you look at one wall in front of you, you can perceive it as an object.
If you see it from the side, you understand that it divides space.
If it then connects with another wall, you begin to see it as a container of space.
At that point, the wall functions as a shelter, protection, a sense of security from the elements. This is the most primitive function of a wall, but it is a part of any important architecture. Creating spaces that inspire a sense of well-being is the main goal of the building walls.
A wall must assert its presence in terms of its form and materiality, to make you understand that it has its own power or presence, but it must do so in a way that inspires and does not force or intimidate.
It is important to be forceful without being intimidating or overly elaborate.
by Tadao Ando