Philotomy Jurament
First Post
The "logical" explanation for why there are wandering monsters is separate from their game function, which is inherent in the rules for XP, time, and exploration.I never saw any evidence that wandering monsters were imposed as a limit to exploration and mapping. They were simply an application of "logic" that monsters would not just sit in rooms waiting for adventurers and would instead mill about.
The default assumption of the original rules is that your characters are after "fortune and glory," with a big emphasis on the fortune. That's why treasure awards XP: it's an abstract "story award" that fits the assumed paradigm. Under the system of XP awards that became standard (from Supplement I Greyhawk on), PCs could expect around 80% of their XP to come from treasure, and only 20% or so from monsters.
With that kind of setup, fighting wandering monsters has a poor risk:reward ratio. Wandering monsters rarely have any treasure to speak of. They become something to avoid, for game reasons, as well as for story reasons. The threat of wandering monsters encourages players to set a goal and keep it in mind, to avoid wasting time on things like detailed mapping and searching every little inch of the place, et cetera. In that sense, wandering monsters certainly act to limit and focus exploration.