I've always been of the opinion that there really is not such thing as wasted effort where scientific exploration is concerned. Even complete failures teaches something, even if it's a 1,000 ways to do it wrong. It's still knowledge that creates better understanding.
So I'm not against SETI or searching for signs of technologically advanced extraterrestrial life. But I also think that even with all the advances in data analysis, radio telescopes, etc, that most likely benefited from SETI research, the deck is still stacked against finding "aliens".
It isn't just the vast distances involved, which after all are so vast that it's nearly impossible to wrap your head around. It's also the massive time scale we're talking about. You don't just have to point in the right direction, you need to do it at the right time. Because there's no evidence to show that once (and even if) a civilization starts broadcasting that they continue indefinitely.
For example I can easily see in 50 years or so Earth going radio silent. OTA is being quickly replaced with cellular technology. Broadcasting using high power radio towers is simply inefficient, compared to cellular tech. So a combination of hard line/highly focused satellites and cell towers for the "last mile" makes a lot more sense.
How do we know this isn't a common developmental path for any civilizations that utilize OTA broadcasting? As for the possibility of them attempting to contact us by beaming a signal into space the same problem arises. What direction do you point in, and are you doing it at a time where someone on the other end will "pick up the phone". Chances are no...
"Imagine you are sailing a boat on a stormy dark sea and see a weak light from another sailing boat in the distance. Will you take out your gun to shoot him, or find him so you can help and depend on each other?" It's a nice thought but if I see a weak light out at see then it's most likely a Chinese fishing vessel stealing fish under cover of darkness. Fast forward a year and they'll be claiming the whole sea and surrounding islands as their own.