Keep in mind that
1. A quest like that is in Oblivion, as others mentioned.
2. The quest can't be too hard. Because if the player just happened to have left all his weapons and armour at home, or was critically injured when the quest happened, he can be stuck in the quest forever without reloading. And there is nothing worse than being forced to reload for no fault of your own.
Good points.
I would have to say I enjoyed The Bloated Float quest in OB, but the irony of it was that I would never have discovered it on my own. The only way I learned of it was when I was looking at the UESP.
Now, I'm not sure if that's a good thing or a bad thing. I mean, the design of a "forced" quest is fine imo, but if I never find it, what good is having it in the game? And conversely, if it's easy to find and most players happen to trigger it on a regular basis, then it could just be an annoyance. Not to mention it would lose it's "surprise" factor after the first time and become tedious.
Based on those points, I'd say I would prefer random events instead of forced quests, because 1. They are random and unique 2. They are not guaranteed for each player or triggered by the same action and 3. They are better immersion tools because they give you real, in-your-face story and action that has the surprise factor, without becoming stale. Bethesda has already said they have added some things like this to Skyrim, and that they know not to make repetitive nonsense like Fallout 3 apparently had for "generated quests".
Now, don't count on me to explain the exact workings of how those types of events/quests would work, because I just have the idea. But I would like to see what ideas you guys might have about the suggestion.