I think we haven't met any Aliens because we're selfish, paranoid, violent, irrational, un-evolved monkeys with baseball caps and video games and nobody wants to make friends people who happily destroy their environment [and therefore themselves] because it's easier than cleaning up their mess. Our major societies are full of petty, self-serving, closed-minded assholes and i'm a perfect example of that.

The technology-enslavement theory is bunk because humans pretty much tend to self-correct over time. We start destroying the environment, somebody notices, we start pulling back on our rampant destruction enough to keep things operating. An epidemic of fat kids goes on, people start complaining, and schools begin the process of sort-of making their lunches healthier. If it got so bad that we almost destroy ourselves from too much internet use somebody would start complaining and we'd reign back on that too.

Probably the real reason we haven't met any is that they probably have agreements that they don't come down and show themselves to new planets until the new planet's peoples advance their space technology to an appropriate level; ours is still kind of dark-ages technology. Maybe after the military invests we can have a nice big boom in space travel.