What Makes Kentucky Bourbon so Good?

One explanation for why the bourbon and whiskey from Kentucky (and really, is there any other kind?) is so good? The water:

Kentucky’s water is special. It flows through limestone, which makes it high in magnesium and calcium—minerals that also contribute to the magnificence of the state’s racehorses— and low in iron. These characteristics are good for fermentation and for the eventual flavor of the whiskey.

Also, by legislation, whiskey must be aged in a barrel for 2 years before it can be referred to as bourbon.

What Makes Kentucky Bourbon so Good?