Disclaimer: This post carry some spoilers of The High Road chain, if you care about history.
First off, I'm not primarly a powergamer. I farm stuff when I'm bored, but mostly, I run stuff because I like it, or because I haven't ran it in a while, or because some guildies are going to run it.
And recently, I noticed a trend of Turbine putting some NPCs at the end of chains to be there only to be sure that YOU helped along for him to finish things off. That is bad. I don't feel like a hero. I feel like a henchman that paved the way for the hero to come and win the story.
U13, Web of Chaos. You discover some hidden cultists covered by Inquisitor Gnomon, and ends up trying to prevent the Spinner of Shadows to be set free. You fail, but the spirit of the Silver Flame is still there, and offer you a chance to bind her again to her prision. Cue epic fight. When you finish... it was a plan all along. Lolth appears and froze you in place. Then, the Silver Flame appear and remove you from there because you were helpless. While Lolth appearance was good advertisment for the expansion pack, being saved by the entity you was trying to save/help made me feel bad.
U14, Menace of the Underdark. Three full chains to play around. On the first one, you defeat the drow and save the city. Good ending. Then, comes the second chain. You take a LOT of time to disrupt the alliance of the drow houses, only for the high priestess dominate Ana, and send her to the Demonweb. Then comes the third chain, where we gather a reasonable bunch of heroes to challenge a god in her domain. While I can understand we not being able to defeat her there (tecnically, we didn't even defeated the Lord of Blades, just the quori dominating him), going to the end only to see Ana beaming her HARD feels like I was there only to bring her to save the day. Not epic at all.
U15, Druid's Curse. First contact with the Harpers and a crazy druidic sect that is spreading a weird disease around. You meet an Harper that guide you through the right path (good), and when you find the druid leading the attack, you beat him and the Harper appears to break the cursed staff and save the day. He even lampshades it saying "I did it. We did it". It felts like if we could unstone him during the fight, he could just break the staff right there.
U16, just ran it last night. And it still leaves a bad taste on my mouth. There are those scrolls pieces that we need to find and reassemble. Standard interesting stuff. You gather 4 pieces, and then go for a frontal assault on the Netherense outpost to get the rest. First, you find out that they stole the pieces you gathered AND returned to the fort before you could reach it. Second, you see your work going down because they just reassembled the scroll right in front of your eyes, and use it to open a portal to the Abyss. But up to there, while making me mad, is standard fetchquest stuff.
What I really hated on the quest was there after beating the glabrezu, Elminster and the Harper gal teleport immediatelly to where you are, pick the scroll, say "we came the fastest we could. Oh, and thanks for your help", and leaves. Sure, she gives me the chain reward right after, but for me, it felt a lot like she just got the scroll, got the praise of her Harper boss, and I was taken out of the picture.
I want to feel like a hero. I want to get to the end of a malicious cabal plot and be the one saving the day. I want to discover new stuff and go out telling others what I found. I want to face a raid boss and defeat it by my own powers.
Just take as an example the very first chain in the game: Khortos. You find out that a dead guy is not really dead, uncover a spy of the sahuagins, save the mayor daughter, find the not-so-dead guy and convince him to help against the dragon, and finally you invades the lair of a powerful white dragon while a bunch of much more powerful NPCs than you act as a decoy, so you can save Khortos. I didn't faced the dragon in combat there, but being the responsible to break the mindsunder made me feel like the hero I want to be.
Another example: In the end of the Weapon Shipment, a pit fiend arrives to end us once and for all. Then suddenly, a cannith warforged titan appears and face the pit fiend himself. How this is different than the end of CitW? We can ATTACK THE PITFIEND. There is it. This is you being the hero. The titan arrived as a very powerful ally, but you can take the lead and attack that devil with your own strength.
Phiarlan Carnival: You defeat Malicia after Phiarlan soldiers got dominated.
Sentinels: You defeat Captain Tew and take back the Deneith Tower the pirates have dominated.
Reign of Madness: You save the Twelve from basically a demigod.
The Dreaming Dark: You went to Dal Quor to basically reenact what the Stormreaver (a legendary giant hero) did centuries ago.
Please, make more quest chains where the NPCs do not appear in the end only to show how powerful and awesome they are. I never liked it on PnP, and I'm not going to like it on DDO.