In my post Immersive vs. gamey in D&D Next, I mocked action points as a metagame resource that forces players out of character. “Perhaps action points are like that surge of energy that brings Rocky off the mat at the end of the final movie bout. Why does Rocky only get that surge in the final fight? He always saves his action point until the end. (You can see the scene where Paulie coaches Rocky to save his action point in the director’s cut.)”
Based on the post, you might suppose that I categorically hate action points. Not so. Although I dislike gamey resources in a game focused on role playing, I don’t draw such a hard line that I find something as innocuous as action points terribly upsetting. Sure, you cannot manage your character’s action points while immersed in character, but you need not step out of character for long. When I play, I certainly enjoy spotting a moment when I can spend an action point to make a big impact. Enough players enjoy action points, that I can accept that they could merit a place in the game.
In a system like Dungeons & Dragons 3.5 or D&D Next, the fourth-edition action point mechanic, where players spend a point to gain an action, would just give players a fun boost. But ironically, this 4E mechanic works badly in 4E because of the big, potent daily and encounter powers endemic to the system.
Once upon a time, only magic users and clerics possessed anything like daily powers. Because few cleric spells did much in combat, typically only magic users could unleash battlefield-clearing attacks or force the boss to save or die. Every other character class stuck with at-will attacks.
The 4E designers sought to grant every class the fun making the grand attacks once limited to magic users. Players of every class suddenly enjoyed the presumed fun of managing a portfolio of encounter and daily attacks.
In 4E, as much as possible, players save an action point and their big daily powers for an expected climactic encounter. When that showdown with the boss comes, the characters unleash everything they have. Every pre-Essentials character can horde daily powers for the showdown, making the first round of attacks devastating. Action points allow characters to double the barrage of daily and encounter powers, making the onslaught twice as potent. By the time a guy like Juiblex, demon lord of slimes and oozes, gets a chance to act, he’s prone, immobilized, dazed, suffering -4 to all attacks, and has his pants around his ankles. (In fourth edition, even oozes are subject to the pants-round-ankles condition.)