Historical precedent conferring power, high standing in the community, high visibility in the media. Secretive, arcane institutional practices. Probably one of the most punishing courses in terms of the trade-off between volume of work, real-life job "prospects", expense incurred during training (correlates with elitism), difficulty of degree, money earned.
It is probably however the only "high-powered" job that can be got by people who are smart in a wordy way rather than a numbers way.