I guess that it is a balance between minimal knowledge .. which makes for a very minimal and limited monkey-see-monkey-do sort of pilot .. and a very detailed engineering, electronics, avionics, etc., etc., knowledge ... which makes for an unworkable system.
Somewhere in the middle is a sensible, practical, and reasonable middle ground.
In general, knowledge is not a load to have tucked away in the back of the mind .... but, for the average pilot, it probably is better to be practical rather than book work academic ?