Most dedicated racers I know change their cats only if there is a justifiable performance gain or if the cost of a new boat upgrade is little more than the cost of 'competitive maintenance'.
If a manufacturer decides not to build a boat to a rule there must be good reason. Is the rule too extreme, too expensive to manufacture to? Are the boats durable enough? Are there sufficient dedicated racers of a design willing to commit their hard earned cash? Any manufacturer will build what he thinks will sell. Just how big are the largest active F16 fleets?

Cheshirecatman