We communicate in order to barter, develop resources, or expand our territory. We do these things because it helps the species avoid extinction. Can we therefore conclude that life MUST have been exposed to the pressure of evolution to develop the traits that would drive it to contact us?
On the other hand, what would "life" look like, if it hadn't formed in the pressure of evolution? Would we even call it "life"?
Exploration of territory is an animal behavior, which demands an animal shape. If an animal is going to climb the technology ladder that we have - fire, steam, electricity - and then climb that ladder into space the way we have, doesn't that mean it must be a land-dweller - or at least not an ocean or air dweller? How would an air dweller build a rocket or a space suit? How would an ocean dweller develop sufficient propulsion technology?
Perhaps I haven't read enough science fiction, or chemistry textbooks. This is probably not a hard restriction - creatures living in the depths of a gas giant could have very solid bodies but never stand on land. And if they were to explore their upper atmosphere and beyond into space, they could easily build robots to do it by proxy, like we have.
The first question still remains though, and it's the one that really bothers me: Why would they do it? What other reasons would they have than our own?