Concept: NPC Chatter

I promise I'll do a non-concept update someday.

Possibly one of the most ubiquitous elements of modern single-player games is what I'll term NPC chatter, but might be better known as that annoying bastard who refuses to stop telling the player where to go. The phenomenon's most common in FPS games but it's not unheard of outside of the genre. Real-time strategy games can be bad for this too, and the Legend of Zelda series is infamous for, in its more recent incarnations, sidekicks who refuse to stop nagging the player.
The most obvious problem with this sort of player interaction is that it's, to put it lightly, somewhat irritating. In the above clip from the recent and utterly awful Homefront, the audio feedback just won't stop. The male sidekick shouts that he's reloading twice in a row without firing a shot. The player is complimented every time they make a shot. It's distracting, and in a genre like the war shooter that relies on being able to properly focus in a chaotic environment, it's annoyingly unhelpful. Even games that aren't quite as bad as Homefront about this still tend to get annoying quickly, as in the video of Call of Duty I posted earlier.
The primary reason this phenomenon is so annoying is because much of the information is useless. Call of Duty and its offshoots, for instance, will often have NPCs shouting the very same words that are showing up in the player's list of objectives even as the map waypoint changes to show the player exactly where they need to go, and this is probably the least absurd chatter in the game. NPCs will shout every time an enemy dies, every time they need to reload, every time they start to move from cover to cover, which is all useful in an actual combat situation and completely irrelevant within the game. Similarly, in Legend of Zelda there was an audio cue each and every time the sidekick character had something to tell the player about an enemy. This was at least forgivable, despite how annoying it was, simply because it was alerting the player to something they could do. Call of Duty and Homefront's constant stream of combat jargon, however, are just set dressing. The player really has no reason to care if a disposable AI ally is reloading, but it helps to maintain the illusion of a combat situation, at least at first.
The illusion is an important aspect of NPC chatter, not only in the sense of sidekick characters shouting combat dialogue, but also in the case of characters giving the player objectives. This plays back to the concept of the power fantasy; the power fantasy is necessary because the player has no actual agency. In Call of Duty, the player may be the only one taking action, but he's taking action at the behest of an NPC. Therefore, the player has to feel like he's the most important person in the game world, because otherwise he'll wise up to the fact that he's being led by the nose through a series of mildly attractive setpieces. It's not limited to war shooters, either; the Halo series was marked by the presence of Cortana, an AI who constantly talked the player through the game. This sort of NPC chatter is different from simple sound bites in that it is generally the sum total of character interaction the player is going to get from the game. There's not conversation, there's a guy yelling at you to do something.
The issue of NPC chatter is essentially linked to the problem of the player not working as part of a team. In strategy games like Jagged Alliance or Silent Storm, having characters say a line when they run out of ammo, for instance, reduces the need to keep an obsessive eye on the interface. The early Rainbow Six games placed a great deal of emphasis on radio chatter, as the game was about coordinating a strike force that was larger than could be feasibly micromanaged by just the player, making the other characters' radio messages the only way of keeping track of their progress. The power fantasy inherent in most games ruins this, though. The game wants the player to feel like part of a team, so the NPCs constantly update the player on their status, but it also wants the player to feel powerful, so there's no reason to listen to the NPCs, and at the same time it has to keep the player on track, so no matter how powerful the player is one NPC will always have absolute authority over them. It's this sort of schizophrenia in design that's emblematic of many of the more obvious problems of modern game design. An element of the game can either be important or it can be useless. If it's both in turns, then it fails to be either and just ends up being annoying.