Suggestion: Bring back the little speaker icon to control the master volume. It was easy to use, self-explanatory, and a no-brainer; people used it. The replacement Kmix piano key mixer applet is too busy, ugly and complicated. A simple icon is better for the average person.
You mean YOU used it. I don't think kmix is ugly and complicated. It might look a little busy, but that's because there's a lot of options/volumes to set or not. Looks and works better than most other mixers IMO.
What "little speaker icon" do you mean? Kmix has a speaker icon in the tray.

I think it works real easy. You don't have to look at all the other sliders, but they are there when you need them.