Being that they were trying to tie the episode with The Day the Earth Stood Still, they were definitely trying to make the Archer a "flying saucer." I mean, it's literally just that, but with a nacelle attached because it's still Star Trek. There's only so much you can do if you still want to keep retro sci-fi look.use an actual original design when there's plenty available that would have filled that niche perfectly.
I think it's kinda perfect in that they were able to pull off the look while still giving us a "classic" design.