firstly, FYI, the Phone Speakers Switcher app (great in its own right) also has a configurable setting to allow you to answer and end calls with a FULL press of the camera key. That works very well (only downside is that it also opens the camera app in background on "standby" with a message saying lens cover is closed). That's not much of a problem - I would only use the cam button to end call in the odd ocasion that the phone had a hiccough just as I wanted to hangup. Maybe worth checking out PSS as an additional/alternative h/w option for call control?

Secondly:
You young whippersnapper! If I could get out of my rocking chair and get my specs on & slippers off, I'd give you a proper seeing to :-) Seriously, I do often multi-task on the phone, and depending on what I do, it can quite often be difficult to end the call in a timely manner.