I don't know, Michelangelo's David clothed? I don't think it would have nearly the impact, it's quite an extraordinary sculpture of the human form, and there's plenty you can imagine about him. And, like the OP, I saw his Pietá when it was quite accessibly close, and again, it's quite a thing to see. Sometimes, in art, the human form is just that, and sometimes, usually when only half-clothed or when some prudish Victorian stuck a fig leaf where no fig leaf should ever be does it start to titillate IMNSHO. Thank goodness Michelangelo's David was never fig leafed... not sure what I would imagine if it had been.
But don't you think that certain parts of the body of David, like the hands are out of proportion?