Dan Dare
I completely agree with your first paragraph. However, to compare controlling with musicianship is somewhat misleading, I feel.
I have no doubt that having a love of & interest in music will enable one to deliver a virtuoso performance (more so than a musician who does not possess these qualities). But, are the two professions exactly the same ? Would a person who was not interested in music ever become a professional musician ? I have my doubts !
We do know, however, that there are ATCOS who have no intrinsic love of aviation & pursue an ATC career for somewhat different reasons. What I was suggesting is that it is undoubtedly true that such ATCOS can be as good at the job as an enthusiast.
Enthusiasm is not a prerequisite, but being one helps you to make the effort to be selected, qualify, gives you initial experience (for instance, by starting as an ATCA), keeps you dedicated, improves your peripheral knowledge of the job, gives you extra knowledge (which a non-enthusiast may not have),gives you added experience (knowing the ropes) & helps you through the more difficult times.
As I said, in my experience, "give me an aviation enthusiast any day". - & some non-enthusiasts also !