What I meant regarding speed control is that if we are assigned a speed and then self-adjust, it might give the controller a false impression that his/her speed control worked flawlessly. Of course having to go around just to prove a point to ATC doesn't really help either...
I have seen some captains being a bit too "proactive" with their self speed control though, to the point of having to retract flaps and increase speed on final, just because they "felt" that we were too close to the preceding (but in fact were being caught up by the next aircraft instead). Why not at least give ATC a chance to do their job, and if it's obvious that they are not, then intervene.