I don't think a sub makes for a good analogy.
Now, that I've looked at the Bridge stations more closely. There is a good deal of room besides all the buttons. (Why are all the surfaces at an angle? Does this prevent carpal tunnel?) Maybe there's some kind of lip just high enough to keep a clipboard from sliding off.
Though it's hilarious to picture Uhura picking up her chair, and moving it a few feet to the right, to get a better angle.
Maybe certain rec rooms are time-portioned out. What room was the meeting in Balance of Terror and Where No Man Has Gone Before held in? A rec room?
Whether or not a sub is a good analogy, the point is, it's still kind of a silly question. Who specifically does this YouTuber think needs an office? McCoy had one (we saw him sitting in it), Scotty had one (he mentioned it). They had theirs where they did their work. Kirk had his stateroom with a desk and workstation and any damned place on the ship he wanted, honestly. He did most of his work on the bridge. Spock had the same and again, did most of his work on the bridge. Who else among the regulars needed an office? Sulu? Nope. Chekov? Nope. Uhura? Nope. They had duty watches where they did their work. Sulu wasn't writing reports, he was steering the ship. Chekov was plotting courses and probably doing extra credit study under Spock afterwards - in his quarters on the library computer they all had access to, judging by the monitors that everyone had. Uhura answered the phones. What would she need an office for?
As Maurice pointed out, they had briefing rooms to do their conferences. The question is a non-starter because the person who posed it apparently watched only one episode. All Our Yesterdays or something...