Yes you are all completely right. We can export ESRI Grid, than import it into Qgis, transform it , create completely new contours with 3D value and so on...
but why can't do this ReeMaster directly out of the box. If you export the major and minor contours layer only the elevation information is completely lost.
There is still a 3D view function in ReefMaster, the logically step would be to be able to export directly the 3D volume as Mesh, contour lines or pointcloud with Z-Elevation.
I think it does need someone at reefmaster adding the Z-Value for the export.