Just keep in mind that while a lot of artists are able to create some great looking designs, many are not versed in human cognition and user interface design concepts. You may end up with a great looking interface which is largely unusable, or at least irritating to use on a regular basis. If you're going to go down this route, make sure that someone on your team has a good grasp on UI/UX basics in order to vet the designs that are proposed and suggest changes as needed.
It's certainly something I will look at, we've got a mix of short term requirements and more longer term so this approach seems to fit nicely with the latter at this point