Sadly, your tl;dr post, which seems well thought out, seemed to miss the fundamental concept that game developers have caught on to but some players who I would categorize yourself as a part of have not.
The average person doesn't have time. To do anything.
Do you know why a game like Magic the Gathering so instantly and ridiculously caught the imagination of millions of D&D players all over the world in the span of like a year and is stretching out to two decades?
It's because you can get the experience in 15 minute intervals.
This isn't an instant gratification thing. It's not like, say a movie that is paced like Star Wars to hold your attention. It's a time management thing. It's why Star Control II was (and still is) widely considered the greatest game ever made - because the game gave you something to do and enjoy along the way, and cut down the tediousness of the work or attention you needed to do/give to get to that enjoyment.
That doesn't mean you can't have a long and over-arching end-game that might take you hundreds of hours to complete, but what it does mean is that I can't spend 10 minutes creating my own map or reading over a diary of my own notes because soon it's going to be time to have dinner. Then it's going to be time to tuck in the kids. Then it's going to be time to work out at the gym. Then, tomorrow, I have to put up the Christmas lights. Or go to a party.
A game like Morrowwind, to really enjoy it, required you to generally sit down for hours at a time (sometimes) before there was any kind of pay off. Sure I think the pay off was pretty good, but honestly that might take me 3, 4 or 5 sessions before something happens that actually makes me want to sit down again.
The number of people who have and can create that time without failing some other, more important part of their life are simply too few to build a game around. Game developers have caught on to this in basically the same organic way that every other entertainment medium has.
tl;dr - the gaming industry has evolved to it's gross market. And the market doesn't have a lot of chances for marathon sessions.
I think you may have somewhat of a point but I think an RPG game needs to have some intellegence to complete as well. I love Zelda for just that reason -- it's not hard necessarily to get to a dungeon or the next objective, but it's not easy either (even with the bird and flute. The hard part is once you get to a dungeon you have to figure out where to go IN the dungeon and more importantly how to get there.
I think that would work much better in TES. Maybe you do know where the big bad is, but it might be behind pits of lava, a giant horker with a bad attitude and a raised drawbridge. How do you cross all of those things? How do you convince the guards to let you in to a restricted area? How do you take out the BB in the dungeon? (actually TES is pretty bad about boss fights as the battles were never all that tactical).
I'd love to see both given and recieved limb damage like fallout. It seems pretty reasonable to assume that the dragon ain't going far with a broken or missing wing. destructable barriers are cool, switch puzzles, searching and entire dugeon for a key. Any of that can make the game more challenging, and probably more things than I can even think of. Maybe the answer would be hidden in some lore book.
I'll just make one up
I need to find the shattered gem.
I might have to go to mages college in Anvil to check in the library
I read half a dozen books searching for a reference to that shattered gem.
It's related to an event at a place called temple of the one.
Maybe I should ask the bards college for more clues.
No one really knows where it is, but there's an archeological dig going on at the old site of the Imperial city.
Go to the dig site, chat everybody up
Still know one knows, but they found a ruined guide book in old tamrielic.
Can't read it, but that old mage in the library was a student of old languages. Maybe she can translate it.
go back, she reads it, and I'm looking for the temple district (and there's random stuff about the geography of the city)
archeologists use the notes and the ruins to tell me where to start.
I go there, and there's a giant dragon, who I can either persuade or defeat to get the shattered gem.
At that point I have the gem and may or may not need to figure out how to fix it and re-enchant it for a future quest.
You'd definately be rewarded for lore-houndatry, but it's not exactly like morrowind.