What you are saying is quite interesting: basically if lawmakers need to have the skill of writing laws, then it means that they must be very educated in law matters. Lawyers, basically, which makes a lot of sense. But on the other hand if you restrict congressmanship (is that a word?) to such a small and biased sample of the population, how are they supposed to understand the actual problems of the population at large?

It is the very problem of representative democracy: elected officials need to form an elite of superior intelligence and ability to comprehend the world, yet at the same time be firmly grounded in the reality of everyday people to understand their problems and represent them...