Something that a lot of ui ux designers seem to misunderstand is that design has innate value. It doesn't. Anything that can be attributed to being a design really only has value when it's known to serve a purpose. So your job will be to make sure to have some logical backing behind why a design could work and if it is working, how it's working. It's not hard to see where value is actually created, so show the people the client where design has created that value.