I would say Consideration. I am a designer, and I work with lots of designers. Design is harder than it looks and even brilliant designers don't get it right 100% of the time, but I can see a clear difference between the types of designers whose work "looks right" and designers who have approached a brief with the aim of figuring out what "works right".
It's easier to be the former than the latter both in terms of skill and the politics of the client relationship, and that's why there are so many "designers" and so few designers.
Yes. A real designer isn't just a UI artist. Art is one skill among others. A real designer should also understand: UX, human behaviour and interaction, logic, visual language (architecture, shape, color, animation) and other skills...
Most designers don't get it right because they don't have these skills, they are only artists. And because of that they don't understand why a particular design is better than another or even what their own design expresses.
To do a real design, it asks you to do a ton of research and going back and forth between art and UX. Doing brain storming to implement old and new logic elements in a fashion way.
It's like the iOS 6 it was a big step forward because it was a design: simple, expressive, and functional. The guys who created it understood all of that. Then again, Apple followed the fashion trend more than the logic and did the iOS 7 design criticized even before it was out. The problem, among its specific fashion, was that the design was so flat it was destroying UI information. Plus visual problems: sometimes the color seems to mean something but you find one red button that isn't one, sometimes the shape, sometimes the animation...
