An idea about the metagame role of PoL, and its relationship to alignment:
Before there were special alignment-based Outer Planes, and a million-and-one alignment-dependent magical effects, alignment played (as far as I can see) two important roles:
In the absence of these alignment motivations, it might be very difficult to explain why elves and dwarves were adventuring together (luckily, shared Good alignment overcomes an otherwise deep-set racial antipathy) or why those PCs that are part of organisations weren't busy working for those organisations (in AD&D 1st ed this included Thieves and Assassins with their guilds, Druids and Monks with their orders, and Paladins, who according to the PHB like to cultivate relationships with LG Fighter and Cleric nobility).
A difficulty with these alignment motivations, however, is that they can make the game somewhat cartoonish as real social relationships disappear into the background never to be heard of again, and alignment team jerseys become a thin overlay to essentially hack-&-slash play. Various D&D worlds have tried to handle this in various ways - in my view one of the better-thought-out is Monte Cook's Arcana Evolved, which ditches alignment altogether and substitutes the actual social relationships of the gameworld as the glue that brings parties together and motivates them to adventure.
"Points of Light", with its history and backstory for each race, its notion of points of light as safe harbours for all PC races, and so on (I am drawing on the description in Worlds and Monsters), appears designed to go a similar way to Monte in solving problem 1: alignment will no longer be needed to integrate racially diverse parties, because there will be enough detail about their social relationships in the gameworld for these to do the job instead. The loosening up of the relationship between classes and in-game social phenomena (eg Paladins moving increasingly away from the rather narrow Arthurian assumptions implict in the 1st ed PHB) will also help here.
But PoL (unlike Arcana Evolved) also solves the second problem that alignment used to: it motivates disparate parties to go on adventures, because they are the only ones capable of dealing with the threats that might otherwise overwhelm their only places of refuge in the world.
To sum up: PoL makes alignment redundant by offering a well-conceived way of integrating adventuring parties and motivating them to adventure drawing purely on the social realities of the gameworld - there is no need to impose the dead and heavy hand of metaphysics upon the gameworld in order to make the game play properly.
PoL does other good stuff to, like facilitate world creation and adventure design, especially for new GMs. But I think the above is probably its more important contribution to D&D as a game.
Before there were special alignment-based Outer Planes, and a million-and-one alignment-dependent magical effects, alignment played (as far as I can see) two important roles:
1. It integrated otherwise very diverse parties of PC adventurers (diverse in terms of race and class, and therefore potentially in conflict).
2. It motivated those parties to go and fight particular sorts of foes (orcs, demons, etc ie the dungeons statted up the GM as adventuring sites) while also providing a reason for the game not to degenerate (in the normal case, at least, in which the PCs are mostly non-evil) into an amoral mercanary bloodfest.
2. It motivated those parties to go and fight particular sorts of foes (orcs, demons, etc ie the dungeons statted up the GM as adventuring sites) while also providing a reason for the game not to degenerate (in the normal case, at least, in which the PCs are mostly non-evil) into an amoral mercanary bloodfest.
In the absence of these alignment motivations, it might be very difficult to explain why elves and dwarves were adventuring together (luckily, shared Good alignment overcomes an otherwise deep-set racial antipathy) or why those PCs that are part of organisations weren't busy working for those organisations (in AD&D 1st ed this included Thieves and Assassins with their guilds, Druids and Monks with their orders, and Paladins, who according to the PHB like to cultivate relationships with LG Fighter and Cleric nobility).
A difficulty with these alignment motivations, however, is that they can make the game somewhat cartoonish as real social relationships disappear into the background never to be heard of again, and alignment team jerseys become a thin overlay to essentially hack-&-slash play. Various D&D worlds have tried to handle this in various ways - in my view one of the better-thought-out is Monte Cook's Arcana Evolved, which ditches alignment altogether and substitutes the actual social relationships of the gameworld as the glue that brings parties together and motivates them to adventure.
"Points of Light", with its history and backstory for each race, its notion of points of light as safe harbours for all PC races, and so on (I am drawing on the description in Worlds and Monsters), appears designed to go a similar way to Monte in solving problem 1: alignment will no longer be needed to integrate racially diverse parties, because there will be enough detail about their social relationships in the gameworld for these to do the job instead. The loosening up of the relationship between classes and in-game social phenomena (eg Paladins moving increasingly away from the rather narrow Arthurian assumptions implict in the 1st ed PHB) will also help here.
But PoL (unlike Arcana Evolved) also solves the second problem that alignment used to: it motivates disparate parties to go on adventures, because they are the only ones capable of dealing with the threats that might otherwise overwhelm their only places of refuge in the world.
To sum up: PoL makes alignment redundant by offering a well-conceived way of integrating adventuring parties and motivating them to adventure drawing purely on the social realities of the gameworld - there is no need to impose the dead and heavy hand of metaphysics upon the gameworld in order to make the game play properly.
PoL does other good stuff to, like facilitate world creation and adventure design, especially for new GMs. But I think the above is probably its more important contribution to D&D as a game.
... Oh well... It's fantasy 
