I would have thought that the reason that many links courses have an out and back configuration is purely a function of the shape of the piece of land available and the location of the clubhouse.
Linksland can be very narrow - less than 100 yards wide - and is often further constrained by a railway line running parallel with the coast. Many links courses are squeezed onto just such a property with the clubhouse at one end where there is access. An out and back routing is therefore inevitable.
More expansive areas of linksland such as Muirfield are the exception rather than the rule.
Nail on the head. Casting my mind back to geography 101, it does depend on the sort of links you mean. Its ok to say its sandy country left behind by retreating sea, but it does depend very much on the nature of the waves as they retreated - do we have a high energy system with lots of long high linear dunes (so its long and narrow piece of land) or the more low energy estuarine system with a complex area of lower lumpy land which can have more depth to it. Or something in between.
And then of course, its a matter of whether the golfers got to the land before the farmers levelled it out.
Royal St Georges is instructive if you look at Google Earth. Deal is sort of lumpy like St Andrews, but ust up the road you have the mega hills of Sandwich, but they are odd.
You have something happening to the waves probably caused by the headland the river mouth to the north. Its a strange dune system that sort of radiates outward NW from a point in the village of Sandwich Bay, through the golf course and out the other side into Princes to the North and farming land to the NW. So you have a mixed up complex mess of dunes on the southern end where everything converges, but long and linear out the NW side.
St Andrews of course is also a mess as you have the interaction of the higher energy beach front to the East, with the estuary coming in from the other side. But it is only returning nines because they chose it that way in order to have a couple of courses all returning to the town.
Must be a PhD in there somewhere