Flobadob,
The clue is in the question. Professional knowledge is just that - a level of knowledge acquired to be able to think and perform as a professional. Same with doctors, lawyers etc. Someone has to have that knowledge in the system to allow the less experienced talk, ask questions and improve their own understanding. I think the balance is right now - it used to be that we'd all do PK's, my first was one year and 1 week after finishing Shawbury! Ultimately, as you have performed so well in your PK results, you should be proud of your achievement and secure in the knowledge that you have a thorough understanding of the ATC profession allowing you to act as Sup, LEO et al.