deep 
This planet has had life for millions of years, so what's to say other planets wouldn't?
The bigger it gets increases the possibility of not one other form of life, but multiple lifeforms, inhabited planets, galaxies and solar systems.
And to address time, maybe some of these planets with life were far back in time, some are now and some will be in the future...
yes, this planet has had life for millions of years, and lets say that millions of other planets have had also... the problem is that we have to find life when both planets have life. millions of years isnt a big timeframe in the overall scheme of the universe. its like 1 second in the day. That whole day has thousands of seconds where life exists then becomes extinct within 1 second, AND we dont know where that occurs.
So within that 1 second we have to find where life could be amongst trillions of planets (we can only look at less than a dozen currently) AND that it is currently living.
like mars for instance, maybe it had life billions of years ago. But we missed the timeframe for it. It didnt evolve so its not there now.
its just not so cut and dry that because we discover more and more "out there" that its not inevitable that we'll find them..its a paradox that we will find it more difficult.