Basically Magic in society is the crux of the issue. Therefore, because each setting/DM/game is different in almost every aspect except for the core rules, a logical breakdown must be the presence and influence of magic on the society. So the issues at hand would be dealt with differently for each category or world in which you wish to create/play. For example, the typical breakdown would be:
1. Low magic - Magic is virtually unheard of in practice. Magic users are rare and unique, as are magic items. Only a handful of people in the world ever gain knowledge in the magical arts or come into possession of a magical item, but those who do often change the course of history. This world also has a low level of monsters. The sentient races, if other exist besides Humans, are the primary antagonists. Monsters are as rare as magic and often influence the politics of the entire world. A goblin is not a nuisance to a farmer, it is often the harbinger of a country wide disaster.
2. Fantasy magic - This is the 'normal' level of magic proposed in the D&D system. It expects that magic exists, but only impacts society where powerful magics/items exist. Commonplace magic use to be expected, but unusual. No different than perhaps seeing a police cruiser or officer on duty in today's society. Some days you will see them all over, some times weeks may go by. That feeling you get when you see one, however, would be the same as a commoner would feel seeing an adventurer. A slight perkiness, alterness, or weariness. Overall monsters influence the course of towns and sometimes nations, and other races likely exist. As population centers increase, the percentage of magic users and magic influence increases in much the same way as technology in our world. Small towns may not have much modern influence, but large cities with a large magic influence could be drastically different, like Dubai. In this society magic impacts as much as technology did in say the 1600's to early 1700's. Most of the external magic that exists in this world is a counter to the internal, (the world maintaining balance with the players).
3. High Fantasy - high magic - In this world Magic is everywhere. It is our modern equivalent to technology, and analogous to it. In addition, magical advancements can go hand in hand with arcano-technology, making even more correlations to modern life. Eberron is a good example of this, where there is a world that everyday life is touched and influenced by magic. In this world it is not unusual for 1 out of 4 people to have some magical powers, either through study of a simple artisan cantrip for their labor job, or great study and apprenticeship. This is a world defined by the large scale. As so much magic exists, gone are small time worries of food production, labor, sanitation. As much as technology enhances our lives, so to is this world enhanced through magic. In balance to these great internal magical forces, where countries and nations are often ruled by the most powerful, great external forces must exist to balance the society. These external forces are often other magical nations. Monsters exist, and exist heavily, and often times in nations of their own, the most magical often being pushed to the borders of the 'civilized' world. This world functions on an economy rooted in the magical. If magic were to disappear, this society would crumble (much like if technology vanished for us).
So we see that logically, a DM only has to put themselves in the appropriate 'real world' era and add what level of magical juxtaposition for technology they wish to see the effects on their world.
It would make for a great read, and a great book. Moving into topics such as government styles, Oligarchy, Technocracy, Mageocracy, Theocratic, etc. and how each impacts the different categories. Going deeper in depth and dealing with magical warfare, sieges,construction, life in a magical society, etc.