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Knowledge does make you a better pilot. Granted, it's a bit difficult to understand why you need to know how a CRT works, but I have used the departure formula in N Alberta when calculating bearings in my head, plus a lot of other stuff I never thought I would use.
The reason why you need to know so much about radio propagation is because it is actually part of the amateur radio syllabus, of which the pilot's licence is a cut-down version. It's also very handy knowing that you have to increase the frequency during the day to get through to the ops office on HF to find out what you are doing the next day.
I would recommend that you get every scrap of knowledge that you can, because gaps in knowledge tend to become painfully obvious on interviews.
In the USA, Canada, etc, the stuff you think is irrelevant now actually gets taught to you during ground training, type ratings, etc. The JAA take the view that there's no guarantee that you will get this, so they make sure you get it before you start.
I do think, though, that there is the sense that whoever sets the questions has no deep knowledge of the subject matter - it’s as if a secretary had been given the task, together with a big book to make the selection from. There's a lot needs to be done on the administration of exams. If Canada can have the results back to you within 3 minutes from Ottawa, on top of taking any exam during office hours, then JAA can do it as well.
Phil