"desire to impose one's morality on alien intelligences." Actually it wasn't quite universal. The Baby Eaters (for all their obvious flaws) only tried to change other people's minds by debate and discussion. I was a bit disappointed that humanity didn't try and take the alien poetic argument and respond to it. As pointed out, it likely wouldn't have been fruitful given the Baby Eaters neurology is largely built on recycled baby-eating circuitry, but still.

Although of course it could be argued that the reason why we didn't see the Baby Eaters actually impose their morality was they were the least technologically sophisticated of all 3 species.