Chilli & pilotwolf - 100% in agreement.
Bookworm, I know that this thread was specifically started with the premise of a go - around because of an a/c badly positioned on approach however, if you are told to go around when established on final, who is to say what the reason is?
We all know that you are ultimately responsible for your aircraft and passengers but please do not forget that we are held responsible for the safety of your aircraft, plus all the others, plus anything moving on the manoevering area. You would appear to be making the age old pilot's assumption that you THINK you know eveything that is going on in the surrounding airspace, based on what you have heard on the frequency. Believe me, if I am busy with a runway incursion (or blockage)/ major equipment failure / unidentified traffic buzzing the runway, the last thing I am going to do is get into a discussion with you on the freq. at the time to justify my decision. It will not have been taken lightly. An instruction is just that - please comply with it. By all means, enquire after the fact (preferably by telephone, not on the freq) but let me resolve the immediate problem before presuming to second - guess me.
To repeat what several others have already stated, we not only have the right to INSTRUCT a go-around, we are REQUIRED to do so if an aircraft is considered to be dangerously positioned on final.
You quite rightly state that responsibility is divided between flightcrews and controllers for good reason - maybe it is you that should trust us a bit more.