It depends on whether the employer sees a division between research, development and design. A small to medium sized company would see some overlap of these roles, and in such a case I do believe UX designers should be competent visual designers; but I believe design is overrated and most usability circles (NN Group for one) will put data behind that. NN Group's own website is a great example of effective UX, and the common theme in effective UX is to be an end-user advocate and give function a higher priority over form. So I'm forgiving of a middling designer who can be taught to hone their sense of visual balance. I'm less forgiving of an information architect who misses the scale of a device viewport, fails to include a major feature despite requirements showing the clear need for it, etc. I want to see interface layout conceptualized and developed through from requirements to wires, to prototype, to final product. Tell me a story where your critical thinking skills were employed. That, I feel, would be an awesome portfolio piece and a great conversation starter. Great design would be the icing on the cake.

I won't deny that design is great for the sell to a more plebeian consumer; but enterprise buyers of my services are generally more savvy; they're as interested in usability as I am. After that initial sell I almost always go back to wires and rework. And there's no dearth of trust fund hipsters willing to make a given set of wires look pretty; that said I prefer to offshore it in most instances. Once again, I'm in the enterprise software business, I don't do campaign advertising work anymore.

I won't be shy to say I despise advertising as a culture. In the time I was doing rockstar design work I saw a lot of mid-20s burnout at agencies like CPB etc. as they lacked process and methodologies and followed a very reactive advertising agency production model. The need to think things through wasn't addressed to nearly the degree it needed to be, and the brunt of the pain fell on the production team, not account managers promising the moon.