Hobbits here again,
I had another thought.

Not gonna lie, I've started playing a certain mmo again *cough* wow *cough* and a thought came to me when I was doing a particular fetch quest. I was tasked to collect the horns of animals that were infected by some sort of ailment. The quest giver needed the horns to determine exactly what was wrong with these animals.
The quest required me to gather the Horns, but as I was doing so, I noticed that also on these infected animals were Blood engorged ticks. I knew plain well that a game like WoW would never do it, but what if it were the ticks causing the sickness?

(Do you see where I'm going with this?)
The quest asks you to gather the horns for the quest giver to find out whats wrong. You simply take the horns and return:
You return the horns to the quest giver and the quest continues on as normal

However, if you notice, that there were ticks on the animals too, and you decided to gather a few:
"Have you collected the horns for me to test upon?" asks the quest giver.
'Yes, I have the horns right here, but I also found these ticks on the animals that were infected. Perhaps they could be a reason for this?'
"Yes. YES! That is it!"

By collecting "clues" in some fetch quests, it could open up a slightly altered mission.
Does that make sense?

Interesting idea here. Only thing I would do is make the alternate quest objectives very difficult to open up, something only a very observant player would notice. Some dialogue would have to be written in as well for some quests as well.

Otherwise I like it.

In a fallout game (and to lesser extent) a TES game, proficient in a particular skill (mostly speech) unlocks more questing options either via dialogue or some form of shortcut.

In your example, maybe having knowledge in a skill tree (restoration or husbandry or something) can allow you to collect less horns in order to determine the problem, or do your own diagnosis to earn greater XP.

IF done correctly, it would really bring the RPG into the MMORPG. But it takes a very significant amount of resources. Like instead of three on-the-rails quest, you can only create one quest with three endings or a quest with three different completion methods.

So there is a trade off, but one that I'm sure a lot of people would make.

There are definitely branching questlines, with multiple means of completion. Mentioned in some early coverage from Pax gameplay, where you choose which crew member to rescue, for instance. This is accommodated by phasing.

And speechcraft skills from the guilds, e.g. persuade from Mages (mentioned by Nick in that interview yesterday), opening different dialogue options.

As for whether the specific type of example you mentioned is in, dunno. But that's only one example of how a quest could branch. What's more important is... yes, unlike WoW, they branch

There will probably be more Speechcraft skills than the persuade from mages guild and Intimidate from the fighters guild as well, we just haven't seen all the skill trees yet.