I think that there should be a simple balance factor.
Picture this. For each randomly-generated map of Ancardia, you have two variables that vary across it. The first variable is Danger Level. If the location of a dungeon has a higher Danger Level, then the dungeon itself will be harder. The Danger Level could also present itself in descriptions - if the Danger Level of a forest area is high, then an observant PC should notice battle scars on the trees, lots of tracks created by bandits, etc, whereas a relatively safe area should look pretty much pristine. Cities and towns in high Danger Level areas would be more like fortresses, with tougher guards and fewer civilians.
The other variable should be a Land Value - a dungeon with a high land value would have higher chance of generating higher metals when mined, for instance. Perhaps deeper levels of dungeons with high land values could be expected to house vaults, underground cities, royal treasuries, and even guarded artifacts. Cities and towns in high Land Value areas would have better shops, more productive farmland, etc... and would also attract a higher quality of thief. Think Terinyo as high Land Value, and Lawenilothehl as low Land Value.
Each of these would vary smoothly throughout the map, with moderate (a little below half) Land Value and low Danger Level for the town that the PC starts at. The higher the Land Value relative to the Danger Level, the more likely that a town or city would be placed there. As a result, you would basically expect low Land Value towns and cities to mostly only show up in low Danger Level areas, as high Danger Level combined with low Land Value would mean that it's a risky place to make a town with no resulting gain from Land Value.
Perhaps large Orderly (not Good, just Orderly) cities could inherently reduce the Danger Level of an area, making it more likely for satellite towns to form around it, while large Chaotic cities could slightly increase the Danger Level.
The actual Danger Level and Land Value would be smooth patterns, with jumps possible in the locations of high mountains. That is, if a mountain is impassable, then the Danger Level and Land Value on either side can be very different, but otherwise, any particular square would have to be no more than one value different from an adjacent square.
Just thinking about it - perhaps each value could vary between 1 and 10, with 1 meaning "expect to see rats and goblin scavengers" for Danger Level and "Poorest of the poor" for Land Value, and 10 meaning "be wary of the Greater Undead and the Molochs" in Danger Level and "Maybe the shops will even stock Artifacts" (and "look in dungeon for a Dwarven Hall") in Land Value.
And some other effects could also be seen - weapons shops would be more common in areas of high Danger Level, for instance, whereas high Land Value would be likely to stock Books, Wands, and Rings. Perhaps Hermit's huts could be particularly rare in high Danger Level areas, but more likely to house a powerful being (who may help, or be hostile), whereas the more common Hermit's huts in low Danger Level areas would be more likely to house a woodcutter or a farmer (who may still have something to offer).