I think this is a terrible idea that is motivated by egotistical reasons.
Sadly I think the robots will have taken over and exterminated or corralled the human race by the time this becomes a reality. But I'm all for sending whatever life we think can hack it to anywhere that currently has no life, even if not sentient. Not as good as humans, but still a positive biological imperative type move.
Really? I mean does the biological imperative bridge our most high-order thoughts? This seems quite a few steps beyond child-rearing to me. There's no social norm, or instinct to procreate. It sees to me that then there is either 1) an instinct for the biological imperative that can span our reason, or 2) no instinct, but a reasoned 'honoring' of the instinct. Something else? I can't say that I feel it, or even an impulse to honor it this way.
Just like there was a first animal to crawl out of the sea, there is an animal that has clawed it's way out of the gravity well. I suspect that if we knew more about life on other planets we would see a pattern of species gobbling up resources, expanding quickly, degrading their planet and getting into orbit. To the extent that culture is fueled by a biological imperative which in aggregate fuels a branch of a species to spread it's genes/culture to the greatest extent which it can, I think it's a certainty that something exactly like this will happen at some point in the future. I don't know if it's the Mormons, Catholics, Scientology, or a rich crazy guy, but I feel certain we will see this come to pass. It's the perfect chance to take a swing a creating a "perfect" society. I think we will all see "nanny bots" in our life time, and I am pretty sure that a robot can be taught to raise a human about as well as a great many humans are raised across the planet. Maybe I'm crazy, but mankind pushing life out of the gravity well is the closest thing I have that seems like religion to me.
I think the obvious purpose would be to increase the likelihood that the human race continues on. However, it wouldn't take more than a few thousand years before these descendants diverged from our evolutionary path to such an extent that we wouldn't consider ourselves the to be the same species. Actually, given the vast distance, by the time these embryos arrived, they would be archaic examples of our former selves. We might as well send insects or bacteria to far off planets. Given enough time, you probably wouldn't know the difference of what we originally inoculated a planet with anyway.