Who gets commerce or happiness from it in real life?
Wetlands/marshlands provide valuable watersheds that retain moisture and provide a continuous source of water for streams and rivers. They also naturally filter water and provide flood control. They act as a nesting ground for many migratory species, including valuable pollinators that are vital for fruiting crops. While none of these are as immediately lucrative as a new sub-division, they each hold passive value that would be missed if lost.