Why aren’t there skeletons? Chemistry. Same reason ocean water is ocean water. Something I learned on the 3rd day of Intro to Marine Biology. There’s plenty of calcium in seawater, which is why mollusc shells and other calcium-heavy things don’t dissolve quickly in water, despite a rather intense demand for calcium by creatures such as molluscs and other animals, who can pull it out of seawater and incorporate it into bones and shells and such.
Below a certain depth, however, calcium carbonate (shells, bones and such are made up heavily of this stuff) gets aggressively dissolved rather more quickly than in the shallows. This is called the Carbonate Compensation Depth, or CCD.
The Titanic rests in deep, deep water, well below the CCD. Aside from the animal life that would be interested in mortal remains, the bones wouldn’t last too long, either. And so, once again, basic ignorance of day 1 science shit can be used as a wonderful reason to exploit the dead for fun and profit.