My guess based on playing the course once:
1. The par fives are short enough that most people can reach them with 2 good shots, depending on wind.
2. Many of the par fours have pinch points which require a real accurate drive if the long hitter is going to hit driver. Thus, some of the distance advantage is negated.
3. The fairways on the par fours seemed really narrow to me. Combined with deep rough and significant penalties for wayward drivers, players are likely to play conservatively off the tee.
4. Good, varied par threes.
I was surprised at how short the course is. Nonetheless, it does seem to be a model venue for allowing many types of players to win and does so without the boredom of a typical US Open.