good points 2097. People have become lazy in their terminology, and you are right to bring it up.

I think part of the problem is simply that we like to refer to keyboards by their unique switch characteristic(s). For the Model M it's the buckling spring, for the mechanical switch keyboards (alps, cherry, strongman) it's the switch itself, etc.
In almost all cases, when someone here says "membrane keyboard" they mean rubber dome + membrane. After all, the Model M uses membrane switches and we certainly don't want to confuse those with the mushy crap that passes for a keyboard these days.
Also, we often refer to keyboards by the part that provides that feedback/feel (mech. switch, buckling spring, etc)...and with most dome+membrane keyboards, the dome provides little feedback and all you get is that mushy feel as you actuate the membrane switch at the bottom of the keystroke. Of course, as you rightly pointed out, this is not always suitable either, since with the HHKB pro, it is the combination of the sliding mechanism and the coil spring that provides the feel/feedback (certainly not the capacitive switch!).
I try not to get too legalistic about it (even though that goes against my nature).
