I was taking a walk, quietly thinking some melancholy thoughts about how little I like humans, when a novel idea snuck up and jumped me from behind. There might be an interesting SF novel in this, or at least some serious musing, but I'm leaving for a con in an hour, so I'm just going to record the bare bones of the idea. If anyone bothers to read this, please feel free to add your thoughts.
Thesis: a telepathic species would be much less likely to develop high technology, the sort of technology that could lead to them coming to visit us or to them generating a signature that makes us notice them from afar. This is because technological progress is driven by cutthroat economic competition, both on an individual and a societal level. Because telepaths would, by my imaginings at least, be much more likely to understand each other, they'd be less ready to hurt each other. Peaceful coexistence between populations leads to stability and comfort, but aggressive expansionism, conflict, and a harsh existence tend to bring out new ideas and ways of doing things. Significant technological change tends to be pushed by strong individual leaders, not by widespread consensus, and a telepathic society should be much more run by consensus, rather than by driven individuals. The driven individuals themselves are probably driven more by insecurity and the need to prove themselves than anything else, and being nurtured in a telepathic environment would, again in my imagining, let people grow up happy and secure -- but not driven to change the world.