I do too. Very, very much. There are markers all over to show and start a destroy the TG questline. No one with any sense wants them around. The Jarl, Mjoll, Aerin, the shopkeepers, they all want them and Maven gone. After a point Mjoll even asks you how you are going getting rid of the TG. I think you could originally, and some morons removed it. The way Mjoll mentions it a lot, in the way some quests trigger, very much implies there was meant to be a quest there.
Less morons, more time constraints. There are a lot of little signs in Skyrim that point to plans for more depth in the game than what's actually there. If Beth hadn't been so stubborn with that stupid gimmicky 11.11.11 release date, I can't help but wonder how much more Skyrim could've been.
Personally I loved the Thieve's Guild, the story, the missions, the characters, the settings. For me the TG is one of, if not the best questline in the game.
I do agree however that there should have been more choice. Once Nocturnal was placed into things, despite her having limited involvements with the Thieve's Guild in the past I felt a strong sense of hesitation. I didn't want to sell my soul to a Daedric Prince, however I still wanted to complete the questline, so I did it anyway.
There should have been more choice though. Mercer may have been a Nightingale, but we don't gain any of the blessings or powers (Just the armour, which we have before sealing the deal anyway) until after Mercer is defeated and the Twilight Sephulcer is restored. That to me says we didn't really even need Nocturnal's favour to beat him.
The way I see it there were plenty of places where you could've made choices, which could either have carried on the story as normal with a few dialogue changes or changed the ending of the guild entirely.
- You could easily neglect Nocturnal's offer when the other two accept it. Choosing to hunt down Mercer of your own accord. This could easily have still led you to Irkingthad and the final confrontation with Mercer, with or without Karliah and Brynjolf as back-up. Hell you could have pissed one or both of them off by neglecting the deal but met them in the temple later on to group up.
- You could side with Mercer and doom the Thieve's Guild, taking an Eye of the Falmer and killing Brynjolf and Karliah. The guild could then take two directions: You could return to them and after passing a speech check, persuade them that Mercer got away after killing Karliah and Brynjolf, or fail that check and have the entire guild turn on you, leading to their demise.
- You could do the above but also still kill Mercer and claim the Skeleton Key
- It should have been possible to keep the Skeleton Key (Without simply not finishing the quest), rather than return it. This could lead to the guild slowly perishing due to lost luck, losing members to either death or simple imprisonment over time until it is returned. (Imprisonment or death could be determined by how wealthy you made the guild before keeping the key) The guild wouldn't be happy about this and you'd be shunned by them until after returning the key. After which point you could set about freeing or replacing lost guild members.
- You could destroy the Thieve's Guild, similar to how the Brotherhood get wiped out. I'd never do it but the simple option would be nice.
- Finally. The Skeleton Key was supposed to be this very powerful item in Mercer's hands, but it really didn't seem to do that much. For something meant to enhance his skills beyond any natural thief's, simply being able to unlock any door isn't that impressive. They could have given Mercer dragon shouts (Though the shouts wouldn't actually be audible, only their effects applied) so he could use Elemental Fury, Whirlwind Sprint etc. Anything that would make him a more formidable opponent and live up to the need to become a Nightingale. In previous games it may have only unlocked doors, but it was supposed to be far more formidable this time around.
I loved the Thieve's Guild questline, it's easily my favourite, but it still could have been better. All guild questlines could have been better, all they needed was a little more length and choice. It would also have been nice if each guild had a joinable rival faction, e.g. joining the Silver Hand to wipe out the Companions, but both guilds having their own dark secrets that could push you toward or away from them. (I.e. The Silver Hand seem as if they were originally planned to be vampires and of course the Companions werewolves) It would also have been nice if certain things weren't a requirement to reach a high rank, I might not want to be Arch-Mage or the Harbinger, or become those things but via a different way.
So many missed opportunities.
Krosis. :'(