Carl,
The rough lines were established by the USGA for the 2002 Open and kept in place ever since. The reason, whether one agrees with it or not, was to give as close to a U.S. Open experience for the everyday public player as possible. These lines were established by Tom Meeks who is now retired.
Mike Davis who took over for Tom has a different view of course set-up and this includes the width and locations of the fairway/rough lines.
In the last year,though most haven't noticed, there have been several small changes in these. This was to begin favoring certain sides of fairways in an effort to bring back some of the fairway bunkering into play for the coming Open. In addition, Mike also WIDENED several of the fairways for the Open and issued a memorandum to Bethpage and all future Open sites asking them to consider widening the fairways for everyday play. He doesn't believe that the courses should be "Open-tough" for the everyday player. I expect that the fairways will begin being widened at bethpage beginning later on this summer in response to this.
Tilly's original fairway lines brought 90% of the fairway bunkering directly into play with fairway areas directly into the front or side of many of them. A surprising example of this for most is the 11th hole. VERY FEW players have ever experienced the right side of fairway as it originally extended all the way to the farthest right portion of the bunkers that seem impossibly wide of everything. In other words, the fairway was some 80 yards wide at that point. Tilly never planned on all those lost balls!