Coral actually had the key to this a couple of pages ago; know [or at least have a working knowledge of] the other man's job!
Having spent a bit of time observing and dealing with ATC, I've many times queried my colleagues intended course of action in the TMA due to its potential to affect the ATC environment. They have always had no idea of the 'knock-on' effect of their intended action. EG; if asked to hold a speed to a DME distance and its' not working TELL ATC that you have to slow early, don't just do it!
As to professionalism; while many attempts have been made over the years to get QF pilots to go to ATC liaison events, the usual answer is "How much are they paying me; is it a training day?" or "They're there to serve us; why do I need to know anything about them?" Sad
Conversely, apart from chaps going to the US to look at CPDLC with the FAA [comment after landing and taxying at LAX: "There are a few people in Oz who should see this!!"], I haven't seen or heard of an ATCO on a QF flightdeck for years.
However, in long range flying, it can be extremely advantageous to know who conflicting enroute traffic is and their a/c type. Horse for courses.
G'day
