Yes, we've agreed on that, and I mad it abundantly clear that without bending space or some such you were not getting anywhere anytime soon. OTOH, without f=ma, you are not moving at all.
Meh, they were all designed to look impressive but people who where more artist than scientist. 2001 got space travel right, and at times it is boring; I could not get my kids to sit still to watch it. Star Wars does better that Star Trek in the 'ships look functional' department.
The original Romulan war bird, which I believe was only used in one early episode, had a broad flat back so it could display a war bird emblem (because, as we all know, evolution is always parallel down to the nth detail, so of course Romulans had raptors (original meaning; hawks, eagles, falcons, and such)). And so it goes. Every thing about TOS is 'because it looks cool', not 'because we thought it out and this makes the most sense'. Trying to fit a rational scientific framework is after the fact.
These ships all bend a bit of space time around them. Wouldn't a compact shape, something like an egg, make the most sense? Presumably, this is the most energy costly thing they do, and would be the thing they need to most optimize. Where would you stick the engine? Maybe dead center, because "Hell, if it fails, we're screwed anyway" and "Might as well give it as much shielding as possible".
What you wouldn't do is stick a long spar on the front of your ship that needed would be contained in that warp field, unless for some reason, your entire engine section was lethal and needed to be separate, in which case, what's up with the broad, thick wings? The Discovery in 2020 was long for that reason, but the living section was a ball, and the spar was just that, a long structure for transferring force from the engines way in the back. (basically a tower, if you view thrust as 'down', and it does indeed look like a utility tower)
So, I ask you, which of these two scenarios makes more sense:
A. The federation thinks that dragging along a bunch of extraneous whatever is good ship design.
B. "Hey, you know what would look cool? A saucer. Space ships are saucers, right?" "Nah, it's been done. The Jupiter II was a saucer." "Well, maybe we could have a saucer that's part of a ship." "That could work." "I'll stick it on top."
I might design a ship that looked like the Enterprise. It would be much smaller, and you'd drive it from the bottom section. The removable saucer section would be for delivering the pizzas.
Reminder, this is fiction. All the retcon in the world doesn't change that. The plotmovium of the week does not make it actual science.
Do we have real world counterparts? Yes, we do. We have structural integrity fields. It's called strength of materials. Do we have inertial dampers? Why, yes, we do. We have cushions, and body orientation, and restraints. Do we have multiple engines as sources of power? Yes, that as well.
Consider, in Star Trek, the fields are able to hold an atmosphere against the vacuum of space, yet a shuttle can arrive and depart though it. Orly? And this makes more sense than, oh, an airlock? Or better yet, what we currently do, dock on the outside and come in through a sealed passageway?
The inertial dampers of Star Trek implies anti-gravity technology, and indeed we briefly see that in use in one movie. It should be ubiquitous. Star Wars gets that.
Where are the robots? We have one android character, his failed brother prototype, his failed daughter, ... did I miss any? They should be all over the place. Star Wars get that.
Warp field; well, we don't really know, but compact would make sense, see above.
Extra engines, generally dedicated to a specific purpose, and power is not generally reroutable. Reroutablity of power is costly on a mobile platform. It works fine on the ground on our non movable electric grid. It works well in a large facility, like the pneumatic distribution systems that used to be in vogue, or the huge stream plant that powered the archaic steel mill I once worked in. An airplane or ship may have extra engines, and be somewhat functional if they are not all working, but they don't swap power between them. And they are hampered in their mission.
All of this, though is essentially superfluous. Gene Roddenberry created a vehicle too tell stories. He had an agenda, but it was not about creating great science fiction, it was about social narrative. That is was enjoyable space opera as well, eh, that's kind of gravy.
Also, the things that are missing in Star Trek, like robots? Cost.
I don't recall it. Seems like if you disconnect the saucer near the battle, you're leaving a very vulnerable target. If you leave it a good distance away, you are stranding it if you get destroyed, and at the very least are committing to backtrack and pick it up.
I'm going to stick with someone though it looked good, and everything else is rationalization.
If you ever see the episodes, you will probably cringe, and wonder how anyone ever watched them. The production values were not up to current standards, and William Shatner's portrayal of Capt. Kirk is notoriously over the top. Mostly, the stories are pretty good, and Early NG is a recap of a few.