Animals need to fit the context and settings they are placed in to avoid being tacked onto the game, I never really brought them up as an issue within my post. I do disagree entirely with your second statement though, as NPCs are important and contribute (or can contribute) significantly to the game. They fill the world that we are fighting to save with character, emotion, lore, story and sense of place. NPCs are the driving force behind player decisions influencing what we do, who we hate and how we do things within the world. Now not every NPC needs a sweeping and grand role such as the mechanic but they can still add to the world. The issues myself and hundreds of other people have is that even the leaders of movements/ factions within the game are almost completely and utterly lifeless so far, despite being the NPCs with the most potential they are simply storekeepers who give us no reason to even consider their ideals or goals. Halo had Cortana, Infamous 2 had Reggie, Mass effect had Joker, The Walking Dead had Clementine, The Last of Us had Ellie so don't try to say that NPCs have nothing to contribute to the protagonists story. Because we have enough examples to prove that isn't true at all.

So, what you're implying is that not only should NPC characters be a vital role in the storyline and sequences, but actually influence the decisions each guardian makes throughout their journey. I can see that being the case with influential guys like Dead Orbit and hopefully even a side step with a Crucible Vanguard, like Lord Shaxx actually acknowledging your efforts.

You're naming off a single individual NPC for the lead protagonist, and a companion one at that. Isn't that what your Ghost is for, to add voice to a particularly bleak or awe inspiring situation? Seems that way to me.

Ok try Anderson for Mass Effect 3, the stranger (the end stalker)for the Walking dead, Marlene from the last of us, Marcus from borderlands and the guards from Skyrim. With companions aside even copy paste NPCs like the guards of Skyrim can add to a game. Also Companions are simply great examples of NPCs as they are non player characters with greater roles, whereas the Skyrim guards are great examples of NPCs with smaller roles done incredibly well.

They are all good additions, that's a given but overpopulation of a game by all-too-detailed NPCs can provide too much of a distraction in what is for all intents and purposes, an action driven RPG FPS. A non player character only needs 4 or 5 lines of dialog each to provide enough background noise to a scene to make it come alive. And from a simple walk around of the Tower, it has that in spades.

4-5 lines of dialogue may be good for some NPC but we are really pointing out the fact that even the leaders of factions/organizations (high value NPCs) in the social hub are simply vending machines at this point. Also having detailed NPCs isn't bad as the player should be able to choose to engage these characters. In what game has an overpopulation of detailed NPCs become a problem exactly? Players engage NPCs, if it is the other way around it is almost always leading to action or progress.

Well yes they are vending machines "at this point". Everything we believe about the current state of NPCs is pure speculation until the final release. We haven't been granted any direct missions by the class leaders yet, but it could still happen. But regarding the vendors, what would be the purpose of striking up a lengthy conversation with a gun merchant? All most people want to do in this particular kind of game, is stock up on one use items and maybe grab a new weapon. I don't need to know a vendors life story unless it has a particular effect on my overall game or mission. Barring in game cutscenes, almost all Bungie games have had superficial-level-only conversations with NPCs. Overly detailed NPCs would derail a chunk of time from a game that for the most part is about travelling across a star system and killing enemies with varying types of weaponry. In a traditional, branching 40+ hour RPG, interactive conversations are of course necessary because they are narrative-driven. In this type of game it's action and spectacle that speak louder than words.