Joe - not a direct answer to your question, but my honest experience with a range of budget/middle of the road golf courses over the years, and a few good or very good ones. In short, rough is a cheat, a short-cut to an end/goal that is itself a cheat.
1. For banal courses with little architectural interest (i.e. with little playing interest other than the simple fun of hitting a ball with a stick), rough is used to give the appearance of said interest. If the greens are boring, and the surrounds uninteresting and the tee shot uninspired/straightforward, taking an 80 yard wide fairway and cutting it in half with 20 yard wide strips of rough on either side doesn't change that reality one bit; but since it is a cheat utilized by countless courses (including the ones down the street and around the corner), everyone bands together and just hopes that no one yells out that the emperor has no clothes.
2. For better courses, where the greens and surrounds are of some interest (i.e. they reward the playing of an approach shot from one side of the fairway or the other, or on a Par 3 call for some thought/imagination in terms of where to land the ball), generations of golfers who are not nearly as good or smart as they think they are have fussed and fumed that, for example, a "poor drive" (by a higher handicapper) that doesn't fly a long way and fades off to the right isn't punished enough, and indeed seems to produce an easier approach than their own booming draw that ends up on the left side of the fairway. So after many complaints, the committees (comprised of golfers also not nearly as good or smart as they think they are) decide to toughen up the course by adding thick rough down both sides -- never stopping to acknowledge that a) this doesn't do the booming draw any good, but only punishes that higher handicapper, or b) that inadvertently or not, that higher handicapper has smartly played the hole as it was designed, from the right side, and so should be rewarded.
No 1 cheats the game itself and golfers along with it, No 2 cheats the spirit of the game, a game of angles and of opportunities (to play a given hole or an entire course or the game itself in many different ways). The sad part, it seems to me, is that this kind of cheat is now built into the very fabric of golf in North America (at least where I play the game) -- i.e. far from being frowned upon, it is actually planned into the design from the start.
While there haven't been many new budget/mid range courses built in the last decade or two, I have played several of them, and this is what I find: from tree-line to tree-line, or from artificial containment mounding to artificial containment mounding, there is a hundred yards of space. That means that the architect/builder either cleared a hundred yards worth of trees or created that mounding a hundred yards apart -- and did so intentionally. Why did he do that? Because he has already planned to narrow the space by using yards and yards of rough, and then ensured that this will be the cased by running the irrigation out there on the edges, those 25 yards per side -- and thereby created the very situation someone like Jeff decries, i.e. a situation whereby it will be more expensive to maintain the hundred yards as fairway than it will be to maintain 50 yards of it as rough.
Again, I ask: why did the architect do that? I mean, if he wanted 50 yard-wide fairways, why didn't he simply create containment mounding 50 yards apart, or clear only 50 yards of trees in the first place? Well, you're guess will be better than mine, but I think it's because a) that's the way things are done when cheating becomes the norm, and b) because his otherwise banal design -- with boring greens, and uninteresting surrounds, and uninspired tee shots -- will not as quickly or easily be recognized as such when the rough (that he has planned from the start) grows in. In other words, he's counting on golfers being golfers and committee men being committee men and on no one shouting out that the emperor has no clothes.
Peter
PS - In the new world to come and that is indeed already here, with increasing restrictions on inputs/water and with an enhanced focus (from all corners) on sustainability in general, that architect would do very well to think his way to a better and smarter design, one that clears only 45 yards worth of trees or creates mounding only 45 yards apart, (i.e. just what he needs and no more, and without any rough to water or maintain in any way) and that features greens and surrounds and hazards that engage and interest us in and of themselves; and those committee members will be well served by waking up to the reality both of the game/the spirit of the game/the playing of the game, and to their own mediocrity in that regard.