When I was a kid growing up in Durham, NC there were three par 3 courses in town; all three are long gone now. Two of the sites have houses on them, and the third is retail space. It’s just money.
Low cost to the consumer means low revenue to the operator, UNLESS you are getting Walmart type volume, and par 3’s just don’t. Most golf courses depend on a regular clientele, whether it’s members, or “avid” regulars, or resort guests, etc, and those sorts are looking to play “full size” golf. If your business model depends on casual, occasional golfers, good luck.