Sunken vessels can create habitat, and they can stimulate biodiversity within the marine ecosystem. However, I would caution actively leaving vessels in place until extensive survey work on those vessels has been completed, if there's no hazardous waste involved in that. The type of material and the composition of material that the vessel is made out of needs to also be considered with that. There might not be oils or batteries or any kind of hazardous materials on board, but leaving a fibreglass vessel in place that is made out of plastics and resins could also create photodegradation over time. I would say the same for tires. I know tires are often also used as a substrate to stimulate underwater biodiversity growth.
Those factors should be considered, as well as extensive survey work, before those actions are taken.