I don't see what people are complaining about, I can totally imagine this ship placed before TOS, as long as you keep two things in mind:
1) The galaxy was a gloriously complex, sophisticated, and advanced place long before the humans arrived on the scene.
2) Necessity is the mother of invention. There are certain styles for warp engines that bring certain advantages, like a cylindrical shape, or a wedge shape, or a rectangle shape. Depending on what advantage is being experimented with will dictate the shape of the nacelle, and it stands to reason via a structuralist argument alone that many races will reach the same conclusions independently.