I recently played a round at Metropolitan Golf Links, one of the better affordable courses in the San Francisco Bay Area. Designed by Johnny Miller and Fred Bliss and built on an old landfill next to the Oakland Airport, it only partially earns the word "links" in its name but does offer a handful of interesting holes.
Hole #16, pictured below, contains a design feature that I'm surprised I haven't seen more on other courses. It is a relatively short par-4 (~370 from the back tees) with OOB all the way up the left side, and in the landing area is a set of dunes oriented diagonal to the line of play. In the picture below I have circled them in yellow. Their orientation is such that the further you shy away from the OOB left, the longer you need to hit your drive to clear the dunes and win both a flat lie and an unobstructed view of the green for your approach. On this most recent play, I bailed right and ended up needing to climb the right-most dune and hit my approach from its peak.
The idea of crossing a fairway with a set of dunes/mounds strikes me as an easy/cheap way to add a lot of interest to a hole, both in terms of initial construction and ongoing maintenance. Contrasting it with fairway bunkers, it seems not only more economical but more fun, as it can produce a wider variety of outcomes for the approach shot.
A similar but inverted example can be seen at a much more famous Bay Area hole, #14 at Pasatiempo. There it is a grassed barranca crossing the fairway, diagonal to the line of play. The line of charm is also up the left, though unlike #16 at Metro, that side requires the longer carry over the ditch.
Where else have you all seen this design feature? Any why don't we see more fairway mounds/trenches/dunes (constructed or natural) in lieu of fairway bunkers?