It does not sound logical. Every time there's an underwater accident (including plane/helicopter accidents and shipwrecks), popular sentiment is on the same line: "why put lives in danger for dead ones" so there must be another reason for sending divers down there (other than feeling logical or not):

- Something related to body identification and insurance.

- Human life is cheaper than ROVs.

- There are tasks that ROVs can't accomplish.

One of the reasons is the bond between the living who continue the dangerous pursuit. It is a statement between them that nobody gets left behind. That is the level of commitment needed; unequivocal and unending.

It's interesting to contrast this with mountaineering, and the many corpses pointing the way to Everest's summit. Some have nicknames.