scuba (& free diving) gives you weightlessness

Not really. Your body and all its constituent parts still have weight which causes them to press up against each other. Blood pressure will still be noticeably higher in the parts of your body nearer to the center of the earth. Your inner ear will still be able to tell which direction is down because the fluids inside it are under the same gravitational force as always. Even a slight density difference will make accelerate so the "floating bubble" effect is nearly impossible to maintain. Also, the drag is very significant, as you mention.

The difference between being suspended and being weightless isn't just a technicality; the distinction has very physical manifestations.