I thought (and it is sort of in the movie) that she was the encapsulation of his love/hate of humanity.
Oh, he absolutely did (love Elizabeth). In many ways, not all of them healthy. She encapsulated humanity for him in the end, even more than Weyland I think. Look at the religious adoration even as he eviscerated her. Hence the iconography!
Matt Hatton, concept artist
(This is the opinion of one of the concept artists who did David’s drawings about David’s love for Elizabeth)