1) I used the word "improbable" because:

Since exoplanets have been discovered, several things became evident:

Our solar system is no more a common system (as we thought) but one kind among many others.
Planets have very often very elongated orbits (the only one like that, here, is Pluto (which isn't a planet anymore and far away from the habitable zone)).
The diversity is just huge.....and that makes our conditions even more rare.

A study shows how viscosity matters at the beginning of the formation of a star system...

2) Claiming life should be in huge number of planets all across the universe is an expression of faith, not based on science (above, the studies are based on observations, simulations, reason, reproducible events-or science).

I saw a program on TV about ET and a SF author (Bernard Werber-I'm currently reading one of his books) said: imagine we are actually the only living forms in the universe, which could be the case, then think of our responsability to preserve them!
Well, I understand what he meant, but I don't agree with the need to absolutely preserve it....After all, we all die anyway and we evolve and what might be alive in a million years will have no recollection what we are as humans.