Pat,
I agree with your theory in general, but the holes mentioned might not be so affected.
Using the yardages given in your post, the strip of rough begins some 50 yards or so short of the green, and ends 20 yards short, which places the creek just over 20 yards from the green.
Perhaps having the rough entices some players ( those with warning track power) to go for the green in two, knowing they have a 'buffer' strip that may save them from the creek if they've over-estimated their ability, or top a shot.