This would seem to fall under the category of "purely penal laws", meaning that they do not have a moral coloration, but if you are apprehended for doing so, you are morally bound to accept the civil penalty (fine or even jail time). For instance, in many places, posted speed limits are routinely disregarded (such as on interstate stretches in urban areas), and nobody is ever pulled over for exceeding them by a few miles, but the law nevertheless exists, and if you were pulled over, the officer would be legally empowered to give you a citation.
Unless it were some sort of emergency, though, such as having to take a gravely ill or injured family member to a doctor or hospital in an emergency, it would be highly imprudent to drive without a valid license.