I went into the final dungeon in Guild Wars 2 and they talk about how the Destiny's Edge unite together to defeat Zhaiten, and the first thought that came across my mind is the last time I talked to one of those guys was level 30. In theory you could be doing the other dungeons to get more about their background story but as far as I can tell those are five losers who squabble about some other guy who died that I don't even know but they're supposed to be important because they're the Destiny's Edge.
But this is hardly unique to Guild Wars 2. In SWTOR you might not even know why Darth Malgus is important to the story even though he's the final boss for the game's overarching story. You may have never seen him up until that point especially if you're on the Republic side.
In fact I think whether a game really delivers or not is when you get to the key events (usually involving a key character, but not a requirement) really delivers. For example I really have no idea who the heck any of the guys are in Metal Gear Solid, but they all manage to come off as genuinely awesome. Yes they talk about the past and whatnot but you don't have to know what happened in the past with Grey Fox to appreciate that he's supposed to be super awesome. I find that a lot of the games simply do not deliver their key characters even in terms of mechanics. Even something as cheap as Final Fantasy's T. G. Cid is often overlooked. By no means is Orlandu a well developed character, but throughout the game you see who the major players are, and you can tell Agrias is a lot stronger than your generic Knight. Then you run into Olan, who has some really stupidly overpowered class ability (Galaxy Stop) that makes the notion you're supposed to help him almost silly, and then of course when you finally do run into Orlandu everyone knows he's some kind of cheat code to instantly win the game. It also puts perspective of how powerful the Beoulve family was, since Balbanes Beoulve was as strong as Orlandu, so even though you obviously never met Balbanes Beoulve, you have respect for this otherwise never developed character just because he was as strong as T. G. Cid.
For a more well rounded example, the Zeal family comes into mind. Outside of Janus, both Queen Zeal and Schala Zeal are fairly stereotypical characters but they all play their parts well, and without them Chrono Trigger doesn't even have a meaningful central story. Sure, you're supposed to save the world but it's rather nebulous why you're even involved other than that nobody wants the world to get destroyed by Lavos. As a boss, both Janus and Queen Zeal are appropriately challenging and as a character, Magus is certainly very unique. He's not necessarily overpowered but he's very versatile and having no default triple magic actually makes him stand out more (he's too cool for combo magic, I guess). Schala, although she didn't do much beyond a damsel in distress, you can argue that the entire purpose of Chrono Cross was looking for Schala. That was also the central theme behind Radical Dreamers I think. In fact, Chrono Cross provides an exact opposite contrast. You know that a Chrono game has to resolve what happened to Schala Zeal but Schala lost every bit of her mystique in Chrono Cross. Perhaps she shouldn't have dyed her hair blonde during her disappearance into the Timestream, and since Schala fails to deliver the rest of Chrono Cross is basically a random mix of sidequests that don't even seem to match up in any meaningful way.
The weird thing is that it shouldn't take that much to make your key characters count. Mega Man Zero series's Omega has assumed some kind of Akuma status and the only words he ever said was "I am the Messiah, hahaha". He certainly has no real presonality to speak of but similar to Shin Akuma, his move set is just so overpowering and yet it matches Zero's moveset exactly that it's almost as if you're playing the character that Zero was always meant to be (he's supposed to be way overpowered compared to everyone else). Of course on the opposite you got the Zero versus X fight, which is supposed to be a big point in the MMX series and it extends even into the Z series (you fight Copy X twice), but while you've entire games foreshadowing this inevitable battle, X versus Zero never quite delivers, especially on X's side, because X was never that powerful as an enemy to make you feel like this fight could go either way.
If you can't do any fancy character development, at least give your key importants something flashy to do. Everyone remembers Orlandu from FFT, even if his character development was nonexistent, because you don't need character development when you're T. G. Cid.
But this is hardly unique to Guild Wars 2. In SWTOR you might not even know why Darth Malgus is important to the story even though he's the final boss for the game's overarching story. You may have never seen him up until that point especially if you're on the Republic side.
In fact I think whether a game really delivers or not is when you get to the key events (usually involving a key character, but not a requirement) really delivers. For example I really have no idea who the heck any of the guys are in Metal Gear Solid, but they all manage to come off as genuinely awesome. Yes they talk about the past and whatnot but you don't have to know what happened in the past with Grey Fox to appreciate that he's supposed to be super awesome. I find that a lot of the games simply do not deliver their key characters even in terms of mechanics. Even something as cheap as Final Fantasy's T. G. Cid is often overlooked. By no means is Orlandu a well developed character, but throughout the game you see who the major players are, and you can tell Agrias is a lot stronger than your generic Knight. Then you run into Olan, who has some really stupidly overpowered class ability (Galaxy Stop) that makes the notion you're supposed to help him almost silly, and then of course when you finally do run into Orlandu everyone knows he's some kind of cheat code to instantly win the game. It also puts perspective of how powerful the Beoulve family was, since Balbanes Beoulve was as strong as Orlandu, so even though you obviously never met Balbanes Beoulve, you have respect for this otherwise never developed character just because he was as strong as T. G. Cid.
For a more well rounded example, the Zeal family comes into mind. Outside of Janus, both Queen Zeal and Schala Zeal are fairly stereotypical characters but they all play their parts well, and without them Chrono Trigger doesn't even have a meaningful central story. Sure, you're supposed to save the world but it's rather nebulous why you're even involved other than that nobody wants the world to get destroyed by Lavos. As a boss, both Janus and Queen Zeal are appropriately challenging and as a character, Magus is certainly very unique. He's not necessarily overpowered but he's very versatile and having no default triple magic actually makes him stand out more (he's too cool for combo magic, I guess). Schala, although she didn't do much beyond a damsel in distress, you can argue that the entire purpose of Chrono Cross was looking for Schala. That was also the central theme behind Radical Dreamers I think. In fact, Chrono Cross provides an exact opposite contrast. You know that a Chrono game has to resolve what happened to Schala Zeal but Schala lost every bit of her mystique in Chrono Cross. Perhaps she shouldn't have dyed her hair blonde during her disappearance into the Timestream, and since Schala fails to deliver the rest of Chrono Cross is basically a random mix of sidequests that don't even seem to match up in any meaningful way.
The weird thing is that it shouldn't take that much to make your key characters count. Mega Man Zero series's Omega has assumed some kind of Akuma status and the only words he ever said was "I am the Messiah, hahaha". He certainly has no real presonality to speak of but similar to Shin Akuma, his move set is just so overpowering and yet it matches Zero's moveset exactly that it's almost as if you're playing the character that Zero was always meant to be (he's supposed to be way overpowered compared to everyone else). Of course on the opposite you got the Zero versus X fight, which is supposed to be a big point in the MMX series and it extends even into the Z series (you fight Copy X twice), but while you've entire games foreshadowing this inevitable battle, X versus Zero never quite delivers, especially on X's side, because X was never that powerful as an enemy to make you feel like this fight could go either way.
If you can't do any fancy character development, at least give your key importants something flashy to do. Everyone remembers Orlandu from FFT, even if his character development was nonexistent, because you don't need character development when you're T. G. Cid.
