This is indeed unexpected. It appears the belief in aliens has been waning instead of waxing as we find out more and more about the universe.
"So what happens if we find all these biologically feasible exoplanets that just don't have any life on them?"
We go forth and put some, of course!
How very human of you,
On the abundance of extraterrestrial life after the Kepler mission Amri Wandel
Some recent calculation of the Drake Equation with estimates of the likelihood and logevitiy of civilizations
Related: The Great Filter and Planets in the habitable zone, the Drake Equation, and the Great Filter