Up to a point I agree. For example, when I first became a training captain on the 332L we had a model of the main undercarriage leg hydraulic valves - all rubber bands and slidly bits of coloured cardboard. I was shown how to demonstrate how the undercarriage hydraulicy bits worked, but when I had to give my first groundschool, I totally floundered. I called in the boss to give the demonstration, which he did. I then asked the class if they understood what had been shown and they all said "No". So I never attempted to use that model again, and when I wrote the groundschool for the L2 and the EC225 it was totally skipped over. No-one has died as a consequence.
I think there was a tendency to fill a 2 week groundschool with "stuff" just to take up the time and provide fodder for an exam - and often (in Bristow anyway) these courses were written by folk with engineering, rather than flying, backgrounds.
Now, there is so much need-to-know knowledge that there is no space for any extraneous crap and it must be cut out! The only reason why we still teach silly limitation numbers of Ts and Ps is because we are required to ask such questions in the exam. As far as I am concerned a pilot doesn't need to know the numbers, just be able to understand the colour coding on the gauge and know when they are approaching or exceeding a limit. Once again, the legislation is way behind the aircraft, and is an impediment to good training, and hence to safety.
All that said... Resilience requires us to have more knowledge that we might need on a normal day-to-day basis, in order to cope with the very rarely occurring abnormal. So a knowledge of how the systems behaves in both normal and abnormal / emergency modes is important, but we don't have to know the engineering detail beyond how it impacts on us in flight.