One of the dangers here is, of course, reinforcing certain behaviors that are supposedly not acceptable in normal society. This includes being rewarded for following tenets like "might makes right" and "if no one else sees it, it didn't happen".
Well, yes, as adults we know that these tenets have some truth to them; as kids -- in much the same way that we devour rulebooks on the 'right way' to play the D&D game -- we are looking for instruction. As kids, we want black and white answers, clear black lines that divide one thing from another; as adults we're hard-pressed sometimes to say, when we're in a certain shade of grey, 'this far, no further'.
This is one of the great things about two of the classic modules of D&D -- B2: Keep On The Borderlands and T1: The Village of Hommlet -- that makes for an interesting comparison between civilization and the borderlands, between the village and the wilderness.
It can be very liberating to adventure in the wilderness -- there are no rules other than outfight, outwit, outlast. The party (and sometimes the individual PCs) are only answerable to themselves. Unless the GM is strict about the cleric's doctrine, there is no higher power other than the PCs and their opposition. Alignments may define what's right and what's wrong for some, but ultimately there is no god, there is no law, there is no 3rd party saying "you done wrong, bud; you gotta pay".
Heading back to civilization -- the village, the town, the city -- is a return to a society that we're somewhat familiar with. It may not have CCTV cameras, but it does have a neighborhood watch; it may not have a fully-funded police force, but it does have a militia or city guard; it may not have overworked judges in criminal courts, but it does have local laws and customs that are enforced by the community. Sometimes this fact is skipped over; the village is just a place to rest, eat, buy food, replenish supplies and improve weapons, and head back out again.
In B2, it's a bastion of order against the chaotic hordes at the border of the realm. You can bet that the rule of law and the maintenance of order is important there -- misbehaving or unruly visitors may find that the community there, regardless of alignment, doesn't like a party of adventurers throwing their weight around. In T1, not all of the residents are obsessed with keeping the peace or the status quo, but are protected by the civil nature of the village, by their reputations, and by an unspoken 'we know him and her, we don't know you' view of the outsider PCs who might start slinging accusations without proof.
This contrast can really be played up to great effect for players. It helps place into stark relief why civilization is sometimes beneficial and sometimes a bane to the individual.
It will also help players come to grips with moral questions and quandries, without necessarily giving black & white answers. And it may teach us something about human nature -- about a sense of identity separate from what other people tell us we are or should be.
As Lord Whorfin said in the cult movie Buckaroo Banzai: Across the 8th Dimension, "Character is what you are in the dark."
In the dark dungeons of D&D, sometimes it is the bright light of personal identity and personal choice that shines the brightest during gameplay.