We could rope in the en.wikipedia.org/wiki/Drake_equation, where the end result N tells us "the number of civilizations in our galaxy, with which we might hope to be able to communicate". The factors leading to N not only may not be complete, but are rather uncertain in each term. Civs may be so short lived, that not seeing them anywhere in the EM spectrum is what's to be expected.
However, I lean more towards the more demanding explanation that we could well be "alone" (there are too few civs to make detection worthwhile). It's hard to believe that we just happen to be in a dead zone where the spectra of other civs haven't reached us or have already passed us by. The evidence (albeit poorly understood) is what we should be going on, not on our hope of there being other civs, and certainly can't be supported by the idea of "easy life". Even if life arises easily (since the dust clouds of the galaxy have rather complicated compounds in them, allowing for interstellar seeding) we still can't deny the evidence of the "silent sky".
The "easy life" concept means that we should keep looking. We should continue a modest search of the EM spectrum for likely signals. We should search for astrodynamic evidence of artificial structures and movements (like Dyson Spheres and other modulations of starlight). But until we get a positive, we have to admit the evidence says: NEGATIVE.
(If pressed to cut SETI funding, I'd cut it. It would be better to expand out into the solar system using such excess funds, rather than continue to blow cash looking for civs that should be too far away to contact at any rate.)