xort -- good thought.
I think some will resist the idea, and forecast that these marine volunteers will simply strip the abandoned vessels, and then leave the too-hard-to-recover bits for the authorities to deal with. Any concrete plan proposed should address this concern. If if the proceeds from everything of value taken from the vessels were to be given to a local charity (preferably marine related), that could go a long way towards selling the project.
The real genius of this effort will be to motivate the actual owners of marginal (but not hopeless) to deal with their issues BEFORE they become the eyesores and hazards that lie at the root of the problem. After several well-publicized recoveries, those owners will hopefully realize that the boat they are ignoring could well become only a distant memory.
You, sir, are an idea man!