Careful here though, I think it's important to distinguish 'functional' concept art with 'beautiful' concept art because if you get hung up on trying to make a concept look like a finished piece of art when you are not a great traditional artist, then it can be a blow to your confidence despite it not being greatly…
I think Pior just meant to make sure that the design itself is functional, not the art to describe the design. Cuz like Crazyfool said you can't polish a turd