Quality and effort visible in the visual communication gives users credibility of the brand. Words are no longer needed as trust is automatic.
The point of design is it's usability. Designs and design applications must first be usable, so that the users recognise the intent and use it without questioning or being in the dark.
Good design means good user experience where your users use your material without trouble and get the message wit no effort, but mos importantly answer to the call you are setting.
A sense of belonging
An identity and a subsequent brand create a sense of belonging for both users and employees as they develop feelings that go beyond the basic product or work relationship.
A sense of purpose
A good identity will fill you with a sense of purpose, it will give you a clearer vision and mission and it will all join it under one roof of the brand, you are creating.
Less expenses, higher success
Over time a good identity saves a lot of money just based on higher success. Better communication means less communication, faster processes based on design experience means less time, and all that means more success and less expenses.