The Israelites wandering in the desert for forty years. The Trail of Tears. The Mongol Invasions. The wagon trains to the American West. History is marked by mass human migration, villages uprooted, families packing everything they have and setting out on a desperate, years-long journey to find a better place. Migration is one of the great human stories, and one that has not yet been the subject of a campaign.
This story is about a journey, and the perils of journeying. Many effects in D&D remove the journey, or take important parts of the tension of adventure away. Fly or Feather Fall remove the fear of falling. Water-breathing removes the fear of drowning. Teleport removes the entire journey.
So, as a guiding point, we ask: what would Gandalf do? If the effect removes the adventure, it will be Rule-0’ed. This currently means that any flying magical effect is straight out. (Flying mounts are another question entirely. Gandalf rode eagles.) For now, tactical effects like Misty Step and Dimension Door remain intact, but are on probation.
As he says, D&D (in all its many iterations) is ostensibly a game about travel and exploration, and yet so much of the magic available to player characters doesn't simply mitigate the rigors of travel, it removes them entirely. Within the scope of the campaign, the GM has ruled out all spells that would speed travel (Teleport, Fly, etc.) but not those that could make other hardships moot. Who cares about having to cross a desert when you can cast Create Water? Who cares about dangerous cliffs when you have Feather Fall? Dark caverns when you can just make Light at will? Your small supply of food spoiling when you can simply Purify Food & Drink?
Low-level spells available to every 1st-level adventuring party can easily bypass all manner of daily hardships. In later editions of the game and many D&D clones (Pathfinder, 5e) a great many of these spells have even been relegated to 'Cantrips' which can be used ad infinitum. In such games all of the gear traditionally associated with low-level adventuring parties (or real-world exploration)--torches, extra water skins, long coils of rope--become completely extraneous and unnecessary. Magic just makes all your problems go away. Poof!
But is this a good thing?
As a GM I often find myself lamenting the lack of mundane suspense in adventures. So much of the fun of "adventuring" in the real world (camping, backpacking, spelunking, etc.) are from the hardships described above. Yes they are mundane concerns, and perhaps not as exciting as swinging a sword against a troll, but these kind of day-to-day fears are exactly the kind that players can relate to. Hunger, thirst, darkness, heat, cold, vertigo. These are things that cause existential dread in day-to-day life. Why would we let a 1st-level spellcaster banish them entirely?
The need for mundane gear also forces important decisions onto the player. Stuff is heavy. Is it more important to take an extra day or two worth of food, or extra ammunition for your bow? You only have so many hands. Can you convince someone else in the party to carry the lantern so you can keep your shield equipped? What happens if the only party member carrying a torch falls in a pit? Now you're fumbling around in the dark trying to light another one while the monsters bear down on you...
What would a modern-edition D&D game look like if you applied the same logic above and got rid of all of the basic utility spells? No more low-level casters providing infinite light, or food with no expiration dates, or instantly fixing all of the daily wear and tear on your gear. Would raising the level of these spells do? What if your Wizard had to use a 2nd-level spell slot to be able to create light? Would you still prepare it?