My guess is that this footage was rendered at a premature stage to wet the whistles of fans like us who are eager to get glimpses of the new show. It's not (relatively) difficult to produce photorealistic CGI of this sort of thing, so the final product will likely be more polished.
That being said, I don't care. The quality of the visual effects are far less important than other aspects of the show. If the producers' goal was to catch the attention of fans like me who care about Trek and its legacy, they totally succeeded. Riffing off of Phase 1 designs was brilliant because it speaks to the possibilities of Star Trek—and in Trek, possibility is everything.
In my subjective opinion, the NCC-1701 is not an elegant design. I find it clumsy, improbable and difficult to justify. It is also unbelievably iconic and beloved. Elegance isn't everything.