I don't want to debate the issue too much but it seems to me you are implying a distinction or conflict that does not exist between --way feedback and ease of use. Or to put it another way that too much use of 2-way feedback can lead to "featuritis". It just doesn't jibe.

I don't think anyone here is advocating displaying the current TV tint settings on the touchscreen! Right now I have a touchscreen in front of me. Virtually EVERY single screen has INVALUABLE 2-way feedback. If I go to the climate page I see the current temp and set point. If I go to the light page I can see the light status. If I go to the windows page I can see if the shades are up or down. If I go to the motorized gate page I can see if the gate is open or closed. And on and on and on. I'm not displaying this stuff because I'm an integrator that "loves 2-way feedback". I'm displaying it because it's integral to the system.

Your volume analogy is a perfect example of why 2-way feedback is so important. You are right, if the bar graph has unity gain represnt 0 that is confusing as hell to people - that's typical of something an engineer designs. But if the bar graph simply represents minimum and maximum, that's invaluable feedback. And I've never had even 1 person even ask me about a volume bar graph - it's immediately intuitive.

Now if your point is that the type of 2-way feedback I detail above is not make or break as you put it, well I'd respond that's just silly. That's like saying surround sound is not make or break and most people can be quite happy with a plasma and a good pair of speakers. Sure they can. So what :-)?