On the other hand Skyrim's Thieves Guild makes Oblivion look like Shakespeare at times. Both games have atrocious writing when it comes to creating interesting quests or questlines. Skyrim may be better than Oblivion, but that's like saying that you'd prefer to take a shotgun blast to the knee rather than the balls.
As far as the dungeon design goes (a continuation to the thread that apparently went to Retardo Land), Morrowind beats Oblivion any given day. Oblivion has larger dungeons, but there's absolutely nothing unique about any of them. There's more to a good dungeon than just the layout, and adding a branch to a brown mess of shit doesn't automatically make it any less shit. You enter a troll cave or a zombie cave or a bandit cave, and it's all just a similar mess of same-looking rooms with no logic or actual structure. I mean, who built the things and for what purpose? Daggerfall's dungeons made about as much sense, but they at least had some variety when it came to the enemy types. All Ayleid ruins are the same, similar rooms connected by similar corridors just in a slightly different way. This isn't helped by the fact that there's no worthwhile loot to be found in any of them, so there's no point to exploring them or spending any more time in them than absolutely necessary. Save for a few specific quest dungeons, you never run into a room that looks different from all the rest or is full of interesting loot. I can't remember a single dungeon from the game because when you've seen one, you've seen pretty much all of them.
Morrowind does have many small caves and tombs, but it also has several multi-level dungeons that have unique elements to them, valuable artifacts or books or whatever (like the scarab plans in the picture that was posted earlier, which alone seems like a good reason to explore that dungeon). Even the smallest caves often have some little unique touch to them, like an underwater passage or a bridge or a sorcerer with enchanted gear. There's lots of variety overall, and some effort obviously went into actually designing the dungeons so that they make sense. Personally I would've maybe cut down the number of dungeons a bit, made the average dungeon a bit bigger and put some more content on the overworld map instead (why do all bandits have to be in some cave anyway?) but overall I like the way Morrowind handled things.
Skyrim is a bit of a mixed bag. The dungeons are too repetitive ("not draugr again"), have nowhere near enough enemy variety and are mostly mind-numbingly linear, but for example some of the Dwemer ruins are pretty cool and more open, like the one under Markarth if I recall correctly. Some smaller dungeons also have nice gimmicks that make them stand out from the rest, like one cave that was basically just one big room with a huge "staircase" in the center leading to the loot on top. Didn't perhaps make that much sense but was still somewhat memorable and different. There's just enough interesting stuff in the dungeons to make you want to check out the next dungeon, even if you'll usually be disappointed in them. Definitely better than Oblivion in any case.
A key thing to remember is Oblivion and Fallout 3 were at the forefront of all-voiced NPC dialog. There was a lot of talk at the time about compression and cost and time factoring in due to the all-voiced thing. I really do think, in addition to firing some good people, Oblivion and Fallout 3 suck on the writing front because of that super early decision to go all-voiced.
I think you're being way, way too forgiving here considering the huge leaps in logic and simply completely fucking stupid ideas that are present everywhere in those games. I agree that voice acting obviously greatly limited the amount of dialogue in Oblivion, but compared to Outcast (which is an early example of an all-voiced open world game, although one with much less dialogue and smaller scope than Oblivion) or New Vegas (which is a recent example of an all-voiced game with TES-like scope) Oblivion, FO3 and Skyrim all do a terrible job when it comes to dialogue. In Skyrim they at least stopped trying to create some kind of "Morrowind lite" wiki dialogue for every single character in the game world, which helped things a lot, but the quality still ranges from passable to outright godawful. I'd say that Bethesda's writers couldn't write their way out of a wet paper bag, but they'd probably fill it with plot holes in no time.