You missed my whole point. It's completely possible to create a character that essentially can access all of what Daggerfall has to offer, at least skill wise. That alone makes replaying with a different focus less valuable. When you create a character in Morrowind you're forced to make tradeoffs, meaning that, unless you decide to do the whole fortify INT exploit later on, you're playing as a unique character from start to finish. This adds a lot of replay value since each character necessarily plays different to the last.
So basically, because it's possible to create a character that's master of all at least skill-wise, you extrapolated that every character is eventually a master of all everything-wise. I think in terms of skills you are probably right, the basic learn by doing system allows to you become expert at all skills, so there should have been some mechanics to limit that. But even that's not entirely true, since some skills are really easy to train and others difficult. To level up the language skills takes forever and if you have them as your primary skills... But build variety in Daggerfall comes mainly from the stat distribution, the advantages/disadvantages and the primary/major/minor skills. The advantages/disadvantages and the skill distribution is permanent and the stat distribution depending on your build can take a while to change. On the skill front, there are no inbuilt mechanics, so you'd have to houserule there (which I never minded doing, but I guess some people do
). My main gripe with Morrowind is, it's difficult to create a character that feels gimped. The let's play you mention, where the guy has to pick and choose quests and avoid monsters - to me, that sounds great.
I didn't mean that literally all skills can be explored by one character but, that a sufficiently large cross section of skills can be experienced by one player. For example, you can put together a pretty varied array of skills in one character that let you experience the magic system, stealth, meele and ranged combat systems without too much penalty. You are also capable of wearing any armour in the game, engaging in alchemy, spellmaking and enchantment.
In Morrowind, the consequences for picking skills at random are much more pronounced since the primary skills category has been removed and the minor skills category has been decreased in size. You also have to consider the natural talents and capabilities of your race. Then you have to factor in how the skills you advance effect what attributes you can increase when you level up, forcing you to specialise whereas, in Daggerfall, you may dump stats as you please.
Regarding house rules and gimped characters, this seems like a pre-internet kind of mentality. OK, let's say you got Daggerfall when you were 13 and it was your first and only open world RPG for quite some time. You bet you're going to wring every last drop of fun out of it. But I'm 21 and have a games, book and movie backlog that are each over 100 items long. I have goals in life that aren't going to meet themselves.
For a game to get even a second playthrough from me, it has to actually inspire me to put in the effort to do that rather than move onto the next shiny object on my list. The kind of grinding necessary to hack it in the early game of Daggerfall with a weak build, the general aimlessness and overflexibility of it's character creation and the relatively bland factions, side quests and dungeons of the world don't bode well for a second playthrough. If Daggerfall had Morrowind's character system, maybe things would be different.
I found the world and character creation system of Morrowind to be so inspiring that I already have three more playthroughs planned. Each character has their own backstory as well, which I have never before been inspired to do. Each character is unique because they each focus on different factions, each have wildly different skill sets. This is all in spite of the fact that many of the early quests are fetch quests and there is no C&C to speak of.
If you want to take multiple quests in a row to send Lady Gwynderbottom or whoever else to sleep be my guest. I however will likely only try such a thing once. I am fascinated by Daggerfall, but not that fascinated.