Science is far from a monolithic entity with inflexible rules. Unfortunately much of the public discourse of scientists, whether to reinforce its legitimacy or to lobby the public opinion for resources for science, reinforces that mythological image.
Well intentioned critics of science, on the other hand, may make unreasonable demands for scientific inquiry, which much of the time will not have any immediate application and still needs to develop; as Faraday famously replied to the Prime Minister’s question about a new discovery — "What good is it?" — "What good is a newborn baby?". Quantum mechanics, at its beginning as an explanation for black body radiation, for example, was practically an intelectual diverstissement for bored physicists, and yet the defining characteristics of the essential technologies of our time — computers and telecomunications — are totally dependent on developments of that early speculations.
PZ Myers made a very interesting and thoughtful discussion of these issues in a recently post, which I thoroughly recommend: Balance.