My apologies - I didn't answer the initial question.
Taking OB out of the equation, I think forced carries tend to be the most unsettling feature for the largest number of golfers.
When facing features of a left, right, or center variety, one tends to accept as a given that he will strike the shot cleanly. His concern is chiefly which direction will that ball will fly.
The forced carry intimidates with severe penalties for a complete mis-hit, which is a much more insidious thought, particularly to the less-accomplished golfer, IMO.
Don't know if that makes much sense, but there you have it.