Tom's reply brings back many memories of designing west Texas golf courses. I recall flying back to Dallas once with a 100 MPH tail wind! The sand in the west Texas Bunkers was migrating to Dallas and points east as fast as the plane. Of course, my newly installed bark chips in my planting beds now reside somewhere in Louisiana, or even farther east.
Flat bunkers are the rule there because of the wind. And in Houston, flat bunkers are the rule because of the enormous rains (Turd Floaters, in local parlance) If it ain't one thing, it's another!
Flat bunkers are usually the preference of better players. They argue that the ball is more likely to bury on the slope facing the green, meaning that a golfer who has missed by 10 feet often has a worse situation than one who has missed by 20 and found the flat, non-burying portion of the bunker. However, Thomas' comments are really ahead of his time, assuming the perfect conditions of bunkers today, the golfer who misses even further has, by far, the most delicate recovery.
However, count me as one who favors the dramatic Tillie/Thomas/Good Doctor flash bunkers unless absolutely necessary (Jim Moore be damned)
just for the shear aesthetic value they provide. Good, artistic bunkering does provide some of the satisfaction of being on a golf course, and strategically, really draws a golfers focus to it. The hidden bunkers aren't really registering on the players mind.
I do agree that we tend to make bunkers larger on expansive sites, as small ones seem to disappear. Variety, however, works everywhere.