Yes indeed the quote from that site:-
Relatively few synths and controller keyboards implement polyphonic aftertouch because it requires a more expensive mechanism.
Is the key, unless you have a synth capable of doing something with the information then it is a waste of time and money implementing the controller.
Note you will not have to scan all the keys for this information only the keys that have been pressed.
wvmarle - not sure what you mean by the keys producing an analogue output.