So, anyone that's done character design/art knows that pretty much the First Commandment is:
Thou shalt known thy Character.
The principle behind this is that otherwise the character lacks personality and zest - i.e. a lackluster picture. For example of this see left and right. They're not necessarily bad per se, but they lack the depth that is achieved through back story (here I'm speaking generally, specifically referenced pics are Horrible on multiple levels, even if we ignore the jelly stain).
If you doubt this is necessary, watch Face Off sometime. (Even if you don't doubt, watch it anyway, the show ROCKS!) Special effects makeup artists have about 3 days to create an original character for each challenge (alien circus, human-bird hybrid, dark elf to name a few). They have a ridiculously short amount of time and Heaps of work, yet the great makeups have enough back story to fill a novel!
I understand this. I agree with this. Yet I still break this rule. Countries and peoples are individual and important characters in their own right. A main character's scene has "extras" in the background. I just feel like drawing pretty clothes in the style of a certain world. The reasons/justifications are endless.
There is usually still some type of knowledge of this person - they're happy or sad, they're on their way to work, stressed out. Something is known, even if this person and I haven't officially "met". Sometimes this turns out characters such as above. These I only knew as servants in Mist, Mahsheean, Kamino's residence.
Yet sometimes the rework is beautiful nonetheless.
(Almost unrecognizable as the same people, I know, but there are hints.)
Like regularly seeing an intriguing person from a distance; some day I will go introduce myself, exchange names, learn their history. At that time I may polish the character up a bit, add some meaningful personal details, but until then, it's lovely background to gaze upon yes?