To the OP:
Morrowind had as much voice acting as did Oblivion and Skyrim, so I don't know where you are coming from on this, you said
"This is what limited Oblivion and Skyrim in terms of RPGing because there are less options for the player and less avenues to go down." Skyrim has much more dialogue choices and seems to have more meaningful convos than did Oblivion. And, my main theme is that the protagonists be silent, which has been the norm in all TES games. So, I don't see less really. Now, I do see they removed complexity from character class building by making all skills easily leveled and the removal of spellmaking as one example. But voice acting has been a part of TES since Morrowind. Personally though, Skyrim has become boring because the side quests don't seem as meaningful/engaging as in earlier TES games and feel more tacked on, but that's just my opinion

I would, in turn, argue that because Fallout New Vegas and to a certain extent Bioware games are examples of good RPG voice acting while not skimping on choices, Bethesda has really run out of excuses here.
The best solution, to me, would be to stop trying to make every single character unique because by doing so you drag down the quality of dialogue for the characters who are actually supposed to be unique. Instead, decide on a select few characters who will receive good attention, spend a lot of time making them stand out from the crowd, and just keep the generic NPCs generic. This is what Obsidian did, generic NPCs would only give you a quick quip before moving on while the characters that mattered were fleshed out and well realized.
Bethesda just tries to make everyone well realized. And as a result, the dialogue gets hamstrung. Makes since too, considering how muddled Skyrim's stories were. In short, they were trying too hard.
I agree with the context on your post to a degree, but disagree with how you compare Bioware games. Firstly, Obsidian has some of the best character writers in the business, so you are going to get great quality there, they lack lack in game polish and typically put out some of the most bug infested games ever. Bioware does a great job of creating characters and telling a story, to me they are the best at this, but I don't get how you say they are somehow superior in dialogue, when over the past few years they removed tons of dialogue by going to voice acting for the player character, something I just cannot stand. Beth has kept the PC silent with text only choices and the dialogue in Skyrim is fairly large and more in-depth than was in Oblivion by far. Beth is just not very good at story telling, though Morrowind and especially Daggerfall were gems.
Bioware has removed so many choices since they were acquired by EA, that I don't feel like I am playing RPGs made by them anymore, rather more like action adventure type games. I'll give you an example.
Dragon Age: Origins had over 1m words of dialogue (written/spoken and may be the biggest ever) and the NPCs all had quality voice acting; the PC was silent. This is probably my favorite all time RPG right there with Planescape: Torment.
Mass Effect, though the PC was voiced, had lots of dialogue and the choices mattered.
Now, we get Dragon Age 2, using a VA for the PC, they only had 400K words for the whole game, and very little of what one does in the game makes any difference in the outcome, e.g. choices didn't matter. Add this same thing on a lesser scale to Mass Effect 2 which was seriously taken down in RPG elements from ME, though you had a few choices that mattered. Now, if you are talking Bioware games from DA:O going back (before EA bought them out), I would agree, but they always used the SP all the way back to Baldur's Gate, with the exception of Mass Effect.