I actually don't buy into the notion that TOS looked more primitive. The equipment on Enterprise generally had a far higher density of controls and such, and if anything, as things advance they often tend to become simpler and more pared down. You can make a case that by the TOS era, starships were capable of automation to a degree where they simply no longer needed to wear their complexity on their sleeves to such a degree.
I agree with that. When I see the interior of the NX-01 it seems more primitive to me than the 1701. Part of that is the submarine appearance of the corridors, part of it is the controls that wouldn't look out of place on a modern space capsule. It's also partly just because the story told me so - but given that we have no idea what future interior design will look like, I don't see anything wrong with that. Perhaps it's also a generational thing - when the NES came out in America, they made it look rougher and bulkier than its Japanese counterpart so people would buy in to it being advanced technology. These days everything needs to be Apple-sleek, no matter who the designer is, which is what I see when I watch In a Mirror Darkly
I don't see the supposed primitivity of the exterior of the 1701 compared to the NX-01, either. It's not like we're going to lose the ability to shape metal into smooth shapes by the twenty-second century, so the rounding on the catamarans shouldn't be a problem. The nacelles of the 01 are perfect as evolving from the Phoenix
, and if you cover them in white and change the shape of the back you've got a 23rd century nacelle. There are primitive-looking greebly bits all over the NX-01, while the 1701 is smooth and sleek. The lack of an engineering hull suggests that this was before the concept came into practice, even if in the 24th century they started moving away from it again. About the only thing that looks primitive on the 1701 is the satellite dish for the main deflector, and that was incorporated into the NX-01, albeit with a different shape and a blue light behind it.
I suppose this is a matter of expectations - I didn't get into TOS until after seeing some of ENT so I had no preconceived notion from observing the increased complexity from TOS to TNG that ships before the Constitution
would be even simpler and more focused on basic primary shapes, with even less surface detail. I wasn't creating my own fictional 22nd century ships based on this conceit (which, again, doesn't have to be true because we can make complexly shaped structures now). And if it's all a matter of expectations, which I imagine most people would have learned to live with in the 10+ years since Enterprise
premiered, there's no need to concoct a BSG-esque scenario of downgrading ships to explain the visuals away.
Edited to add: Also, I think the Kelvin
works great at linking the two visual styles. If you demand a smooth evolution in your ships, there's your missing link. The only problem here is if you must
accept the Daedalus
as a ship that fought in the Romulan War, and we've never seen the interior of it or a detailed model of the outside canonically. The NX-01/Kelvin sensibility could very well be in effect, and there's no reason a starship design can't be revolutionary instead of evolutionary.