Now as to where the aliens are.. on a philosophical standpoint it might be that we are simply not that interesting to begin with. We are volatile, fearful of new things, greedy and vengeful and the simple revelation that there are Aliens might topple our entire worldwide system because of mass panic.
Alien life is rare. And when something is rare, the is no such thing as "not interesting".
Even if the aliens came from a region of space that is totally crowded with civilizations. We are in a region that is completely empty. That would make us special to aliens no matter what.
You are talking about empty regions.. what constitutes a region in interstellar terms? A region in earth terms may be something you could traverse by car within an hour or two so how do you apply that to interstellar distances?
If FTL is possible by any means it might be that Earth-Alpha Centauri is just a short hop around the block, who knows? Maybe we live in a greater region that has a few civlizations and we just didn't encounter them or catch their radio signals because there's a ton of it flying through space on all frequencies.
All i'm saying is that maybe we are not interesting enough to make official contact or we are in such a fragile state that official contact would do more harm than good so we are left alone for now. Maybe we are being studied in secret out of scientific curiosity and maybe some alien students are doing their xenobiology doctorates about us but so far no one seemed to think to contact us directly.