User perspective is the best argument. Presenting your design and justifying design decisions through users’ needs and wishes avoids discussions about taste!
Change self perception. You are not the expert who knows what users want and need; you are an expert at identifying what users want and need, and afterwards apply it to new products and services.
…am tried out the process, and got an introduction to methods that we use regularly in our projects: Personas, Journeys, Interviews, Observation, Shadowing, Cultural Probes, War Room, Ideation, Prototyping, Testing, and Co-creation.