Why is clearly expressing yourself important?

It is important because it will let people know who you are and get people to like you

It also helps one more readily define and acknowledge to themselves who they are and what they believe. Over time, they can then better make self-evaluation as to what needs changing in their lives, their views and their definitions.

Sometimes it is not until one's views are put into concrete actions or Words that they see themselves better in the context of reality.