Though better than Oblivion I will definitely agree that Skyrim despite the beautiful, vibrant world (and Nords
) and occasional glimpse of wit was a disappointment in regards to what is most important in a true RPG; story, characters, character development and meaningful player choices.
The dialogue is decently written compared to the embarrasing baby dialogue from its predecessor (a dev even admitted many of them were affected by having little kids at the time of production) but not impressive compared to the mainstay of PC RPGs like (some of) the Ultima games, Kotor, Witcher, Dragon Age, Mass Effect, (some of) the Gothic games, even NWN, and especially Planescape:Torment, Baldur's Gate and the Fallout series (minus F3 of course which following above criteria is almost as bad as Oblivion).
Fallout:New Vegas showed that the open world concept can still have a well-written, completely dynamic story, intelligent branching dialogue, player choice driven questlines and game world, interesting characters, interesting quests, humor, lore accuracy, consistency - depth. FNV even has an excellent combat system, if you don't mind FPS.
It's a shame as Bethesda has some good writers of in-game lore books - and they did make Morrowind(!) - but seems to have been on the wrong track ever since, even with the few positive backtracks.
