what is the point of users going to the effort of selecting their required active workplane if TC quietly changes it behind their back for no good reason?
You're talking about layers than you switch to workplanes?
Related to layers
The invisible layer warning just means that the layer your drawing is on is "not visible layer", after you draw it it will not show. Nothing to do with workplanes.
RE:Yet I can drawer a cylinder, cone or wedge.
The cylinder, cone and wedge are set on a "visible layer". That's why they show.
When you first selected a "tool", any changes in the properties dialog will stay untell you change it. So, if you change the layer, every time you select the tool, from then on, will be on the same layer untell its changed.
If you select an "object" and change the layer, it has no effect on that tool properties for the originally used tool for that object.