Granted, Drake's Equation:
N=N*fp ne fl fi fc fLcannot be tested in the classic sense with the current state of technology - beyond what the SETI project is doing now, a pop science sampling of a narrow band of the sky for signals. And yes, setting some of the variables is a leap of faith. However, as a statement of probability and a yardstick for progress in our exploration Drake's Equation has value. Value for making public policy? No, I agree with that aspect of Crichton's argument.
Where N is the number of stars in the Milky Way galaxy; fp is the fraction with planets; ne is the number of planets per star capable of supporting life; fl is the fraction of planets where life evolves; fi is the fraction where intelligent life evolves; and fc is the fraction that communicates; and fL is the fraction of the planet's life during which the communicating civilizations live.
But consider - hasn't the count of "dark matter" in the universe dramatically increased in the last decade? Haven't we moved from bring the only solar system with planets to a proven fact that other stars have planets? (Thank you Hubble Telescope) We have seen progress on the accurate setting of the variables N and fp. There IS progress being made and as time goes on, hard science AND pop science like SETI will continue to fill in the blanks.
The Drake Equation also reminds me of the Statistics 101 exercise of calculating the probability that two or more students in a classroom share the same birthday. You solve the problem by calculating the probability that NO student has the same birthday. When you look at it in that light - with each additional student the number of available dates that don't already have a hit decreases - Drake's Equation looks better and better. We are getting a handle on the number of stars with planets, something that wansn't possible when Drake developed the equation. As that number grows, then the chances that NONE of the planets has life and that NO other species has the intelligence to communicate [or the superior intelligence NOT to communicate :) ] diminishes.
Meanwhile, I see no harm in running a SETI process in the background of my computer. If I can interest my child in thinking beyond the bounds of the home planet, THAT has value to me.
Me either, since I "do" SETI with an actual radio telescope with antennas more than 1000 miles apart.