This is a common misconception with hurricanes. The area of hurricne force wind is usually pretty limited, 50 to 75 nm wide, and tropical storm winds usually extend over a 200/250nm swath but those don't cause much damage beyond a few trees or stuff that's not secure.
The problem in this case is thst Mathew will possibly hug the shore line for a fe hundred miles and could cause major damage over a wide area. Every mile counts and if it stays 75nm out, well within th forecast margin of error, there will be a lot less problem.
Same with the Exumas. The center is currently about 30/35nm form th central Exumas and brushed great exuma and the southern cays at the same distance. They will have damage but it may be just enough to make the difference between catastrophic or not so catastrophic damage. Will know later. It may also have been just enough to limit the actual surge which is the big worry