As an artist, I would disagree that art is the least important part of a mod. I, for one, totally look for good art in new civilization mods. Personally, aesthetics is very important to me; while I'm sure there are some great mods out there with excellent design and code, I have a hard time playing them if the art quality doesn't match or exceed the quality of the rest of the mod. I'm even cool with overlooking "boring" or unoriginal traits or unit abilities if the art is good and the mod is aesthetically pleasing.