Hi Mac,
First of all, I agree with your first statement. Bill Coore and Ben Crenshaw were blessed with an extraordinary number of options . There's a famous drawing in the clubhouse that shows the 100+ holes "found" on the property. Certainly, projects with fewer options, a fixed clubhouse and environmental restrictions have fewer available routing "solutions".
Regarding my thoughts about the chosen routing where the two short par 4s are consecutive, I don't have much interesting to say. Best left for the professionals and club members. I'll give it a try. Since a good short par 4 is so fun to play, it is curious that Sand Hills has only two, and they are positioned back-to-back, early in the round. I suppose you could call this a weakness of the course. Both #7 and #8 are outstanding golf holes, very fun to play. Since so little earth (sand) was moved at Sand Hills to create the holes, perhaps specific landforms are required for the specialized purpose of a short par 4. Maybe there were only a few short par 4s on that land. I don't know.
Just taking a shot in the dark. I've played the course a few times, and I'm not an architect, so I'm doing my best to comment.