The sarcastic metaphor and the exasperation that motivates it comes after centuries of scientists being ridiculed, persecuted, and even killed by ignorant people.
Also, because trading vitriol with religious fanatics and ignorants accomplishes nothing. Knowledge is the antidote to ignorance. Not smugness, defensiveness, or indignation (well-justified though all of those things might be).
This conceit can be done well. Mitchell and Webb's little old lady job-justification hearings are a particularly good example. http://www.youtube.com/watch?v=UbXTBPN1HhA