@Yatogami The auhtor's intentions is what is moving the plot forward. But the basic trope is that Damian comes from a family of the upper class, from which high expectations are sought for, and "weakness" should not be shown. The character flaw in that is that identifying your emotions can make you grow as an individual, and it's what hampers character development if you don't acknowledge it. And this is what is happening to Damian, and what eventually has made him grow throughout the series.
When Damian shows his emotions to his father, Anya, etc, he makes a greater and lasting bond and learns that it's ok to do this. Holding back is what causes relationships to break and for someone to feel isolated.