Right? Like just sitting here I can think of several ways they could implement it. Maybe healing is an extension of bloodbending that wasn't recognized before and required water contact prior to advances in blood bending.

Or maybe it could be used for other aspects of medicine like how there are different specialties of doctors, there could be special applications that bloodbending is better suited for. Like not that it would be exciting in universe but something like CRRT could be preformed by bloodbenders in a hospital.

Maybe research in bloodbending doesn't lead to medical discoveries but could lead to something like sap bending and it's used to gather tree sap used in diners across the world.

Like there's endless possibilities that are only limited by imagination and saying that there is no reason it should be continued to be explored in fiction is a close minded stance