Reading Apocalypse World also crystallized a few other thoughts for me. This is not going to be a post about Apocalypse World, mind you, but it is at least tangential to it.
Part of the reason I end up dwelling on the importance of setting in play is that I want my play to have meaning. Not in any grand, deep sort of sense, but rather the small, mundane sense of satisfaction I might get out of finishing a good story. The events and people involved may be fictional, but despite that I am made happy that they have faced their problems, resolved them, and brought matters to a close. Life is, of course, hardly that tidy, and the emergence of new problems is fodder for sequels, but those are matters for another day. Today we have overcome, and we have earned our rest.
This is surprisingly tricky in RPGs. A good ending is something I've talked about before, but it's only part of the picture. The problem is this: the GM has an infinite budget of trouble. There are always more dungeons, new threats and fresh problems to throw at players. Since dealing with those things is the basis of play, that's mostly a good thing. With an infinite budget of trouble, there's no reason anything should ever get boring. However, it is very easy for that budget to turn into a treadmill. Your victory today can become meaningless because the empty spot will get filled by some fresh trouble.
When it reaches that point, that's where I get dissatisfied. The treadmill of trouble usually means that any change I can make in the world is transient or meaningless - it's just new fodder for trouble. In the worst sort of situations, this is why some players end up making lone wolf orphans. It's not that they don't _want_ to have connections to the world, it's just that they've been trained that any connections they have will be used against them as a blunt instrument.
All of which is to say, it's a balancing act. If EVERYTHING is trouble, players have no incentive to invest in anything. But if nothing is trouble, then the game is going to get pretty dull. Finding the path between those things is one of the challenges that every table must face because there's no one right solution.
This is where I come back to the quest for meaning. I invest myself in the setting so that I can, in turn, find meaning in the losses, victories and changes. That helps me find a path towards more trouble, but gives me some anchors to keep me from going over the ledge (as I perceive it). Since other people gravitate towards different paths, the fact that meaning is such a soft idea allows me to plant a flag in a _general_ area without pinning it down precisely.
The trick with meaningful things is that they merit respect, and respect is more nuanced than a simple "on the table/off the table" split. Meaningful things are always on the table, but in a way that _reinforces_ their meaning, not in a way that simply uses them as fodder.
To illustrate, let's say your players have rebuilt an orphange. They've put time and effort into this, and it's an important element of the game. If the orphanage is protected (that is to say, immune to trouble) then it's not going to be threatened by events in play except in purely cosmetic ways. If it's "on the table", then it's now a valid stake in play, so plots threatening its destruction are a valid way to engage the players.
If the orphanage is meaningful, then it can be threatened, but it should not be _existentially_ threatened. That is, the stakes should not be that the orphanage is destroyed or irrevocably changed, but rather that the orphanage is the source of other plots. This may sound familiar to folks who saw my last trick - rather than use the thing itself as the hook, find the things around it and connected to it. This way, the threats _reinforce_ the importance of the meaningful element rather than just treating it as a punching bag for the GM.
1 - Even if they're willing too, it's ultimately meaningless, since everything is fuel for the great machine of trouble.