Alexis has got me thinking. Probably not as deeply or as meaningfully as he'd like (he's got rather high standards, and I'm too busy with earning both incomes in my two income family to hold myself to such high standards in my leisure activities), but he did get me thinking.
So D&D (OD&D, Classic D&D, AD&D), as you all know, comes with both Dungeon and Wilderness Random Encounter tables.
Now, those Wilderness Encounter tables include chances to meet everything from a few wild deer to ancient red dragons as you wander from place to place. And as Alexis points out, by using them as written, how could a merchant caravan ever get from one city to another without being pillaged by 6-60 orcs, a small troupe of frost giants, or a wing of griffons?
But let's take a look at what the charts really are. They're tables for things you might meet in the wilderness, not just while taking a stroll through Farmer Maggot's cornfield.
In the Dominion system in Frank Mentzer's Companion Set, he divides up areas into Civilized, Borderland, and Wilderness. I get a feeling (just a feeling, I've got nothing to back this up quote-wise) that he may have gotten this from Gary (Keep on the Borderland being the artifact that makes me think this).
If this was the intention of the game's creators, we can assume that any game setting should have areas on the world map that are 'wilderness' and areas that are not.
If we divide up any map into Civilized, Borderland, and Wilderness areas [mapping to the alignments of Law--Neutrality--Chaos, interestingly] we'd have Civilized areas where you're likely not going to run into anything besides human-types and normal animals. Merchants, pilgrims, soldiers, wandering minstrels, peasants, etc. Very similar to town/city encounter charts.
In Borderlands, things are getting a bit more wild. There will be more monsters, demi-humans, and giant animals encountered, but still plenty of human-types. And most likely there won't be many overpoweringly difficult monsters.
In the Wilderness--the true wilderness--anything goes. Human-types will become scarce, and those that do appear will most likely be other adventuring types or 'monster' humans like bandits, brigands, pirates, etc.
But what about those merchants that need to travel through the Wilds to get from Port Gunthar to Oxcross? Well, that's what roads are for. Or charted rivers. Or established sea lanes. A well-patrolled and maintained road would count as at worst Borderland, and may be considered Civilized all along its length.
The benefits? Well, first, you've got a bit of verisimilitude in that unlike early CRPGs, your characters aren't the only non-monsters outside of towns. There's also both in-game and meta-game reasons why monsters aren't eating every commoner who tries to go on a little trip.
Second, it provides players with a way to judge their risk/reward, similar to dungeon levels.
Third, it makes decision points on the map. Do we take the long King's Road to Oxcross, or try to save two day's travel by cutting through the Haunted Woods?
Fourth, it reinforces the feeling of Law vs. Chaos as trying to tame the wilderness/wreck civilization, rather than just pseudonyms for good and evil.