

Wallace's words reveal his intent to create a civilization that spans the stars - but he needs replicants that can breed to do that: Wallace is trying to create replicants that can have children. Wallace kills her because she cannot breed.

The desired effect is that Luv fears and respects him more, and that it is now been shown to her how important and urgent the search for the child is (in order to attain the power of reproduction), so it's a motivation boost for Luv for many reasons, too. The final point is a bit of a bonus – he is watching Luv's reaction as this happens, so he presumably knows it has an effect on her.This reinforces the theme of ethics involving treating non-humans (especially those designed to be slaves) inhumanely, as well as it reinforces his own god-dellusions of creating and taking life, as well as it is an expression of his frustration. The newborn replicant is infertile (he makes a comment with the word "barren", though the exact quote is lost on me), and so he discards her. Wallace, as Tyrell's successor, and suffering from God complex, is furiously jealous of Tyrell's achievement of creating replicants that can reproduce (which would be the ultimate method for spreading this species at an exponential rate, population-wise, the surefire way to achieve his main motivation), and so this fury and frustration expresses itself in this scene.This primary goal is more important to him than any one replicant, which, while he professes to cherish and love like a parent, it's more that he loves himself for having the power to create life. he wants to be the "God", or creator, who ushers in this ascension to heaven. he wants mankind, in the trillions, to conquer the stars in flocks (the end goal being more philosophical, he wants to literally have man break out of the universe and into "heaven") and, importantly, 2. Wallace's main motivation is very importantly twofold: 1.
