On a first and more superficial note, usability clearly impacts on how well an user or any people involved in the process will perform a task/job. A well-designed usability experience will help the user throughout his/her journey by being intuitive, easy to achieve goals, and easy to learn. On top of that, even if the user is not able to achieve success, he/she should not feel that it was his/her fault (because normally it will not be). On a similar way, it is important to foresee time to reach goals, waiting periods in the application, security measures, accessibility to extreme users, among other aspects that go beyond color and iconography.
But on deeper levels usability has a deeper impact on the experience. As humans, users tend to link their experience on a website to the brand itself. So a good usability will add points to brand perception. If a company has a adventurous positioning, the UX should also somehow convey an adventurous experience, because this will make the user relate more to the company improving happiness and sense of belonging. User experience goes way beyond aesthetics, and as designers we have to foresee the journey on more subtle ways such as consistency, market positioning, and which feelings we want to provoke in our users.