I want to experience the joy of discovery and finding solutions to quest puzzles on my own without the game hand-holding me through the entire process. If I want that help I want to be able to toggle it on, and then turn it off again.
Why can't I click on the selected quest to unselect it, so that NO quest is selected? I have seen this occur in Fallout 3, such as after solving a quest line. For a while no quest is selected and there are no map markers. But as soon as I find a new quest it becomes actives and cannot be unselected.
At least with Fallout 3, I was able to leave the Replicated Man until the absolute very end to solve, because that quest has no markers on it. I have not yet run across a Vegas quest without markers like that.