another options could be opening new area when you progress in the story and not close the other one like in Fable...
and I must agree on one point that stabbey mentionned, when the valley was distroyed I felt painful and may be more involve, that is true !! but I definitely prefer open world, usually when a story is good I cannot quite it for optionnal quest and those quest come later.
But I definitely prefer an open world even if your actions make some change on that world (I take again the example of those soldiers I mentionned above) and it is good to see that your action have an impact but it is really frustrated when you miss some parts of the game and if there is a wonderful pretty zone it is always godd to go back there for taking a break (in D2 I wanted to go back to see that pretty waitress you rescued from the guards^^)
