I strongly believe that Visual design is also one aspect of user experience design. We can’t shun way visual design in favor of experience design. I understand that getting interaction design requires deep contextual understanding of user, but looks affect usability too. Ex. Apple products. Unfortunately an ugly mock-up of a brilliant idea is often overlooked though looks are just one aspect of design. I often see fellow practitioners not agreeing with this.

Though I agree during idea and concept validation stage, the focus should be more on usability and not on visual design, so that fundamental fixes are done early on. During this stage, we should keep the stakeholders/marketing team focused on structure/concept than getting them hung up on the visual treatments.

Looks are just one aspect of designing, we have to think about the whole user experience of an object.
My understanding says work with the team, based on the need decide when to go with the visual design,
but definitely visual design should not be the key to sell an idea/solution.In the meanwhile we need to question/decide what adds value in the most efficient way. For instance, for testing interactivity more accurately, hi-fi prototypes are of real value.

In other words, both UX design and Visual design are two sides of the same coin.