Why is "Romulan is a dirty word in the writers’ room" for Star Trek: Discovery?

Question

In the first episode "O Discovery, Where Art Thou?" of After Trek, executive producer Aaron Harberts alluded to the difficulty of dealing with Romulans at this point in the timeline.

Aaron made the comment:

Romulan is a dirty word in the writers’ room right now because of where we are in the timeline. The sparks fly when the writers bring up the Romulans.

Now I understand that Discovery is set in the timeline before TOS and after Enterprise. In the timeline this is 2255. We know that this is after the Romulan War.

But the Romulan war finished in 2160. That was roughly 90 years prior. There is some missing piece of information that would make the writers not want to go near the Romulans in discovery.

My question is: Why is "Romulan is a dirty word in the writers’ room" for Star Trek: Discovery?

Answer 1

Between the end of The Romulan War and the original series episode Balance of Terror, there had been little or no contact between the Romulan Star Empire and the Federation. Kirk didn't know what a Romulan ship in service since that time would look like, and Spock didn't have an image to show him.

SPOCK: Referring to the map on your screens, you will note beyond the moving position of our vessel, a line of Earth outpost stations. Constructed on asteroids, they monitor the Neutral Zone established by treaty after the Earth-Romulan conflict a century ago.

...

KIRK: After a whole century, what will a Romulan ship look like, Mister Stiles? I doubt they'll radio and identify themselves.

Discovery takes place approximately 10 years prior to this episode. To include the Romulans in this time frame would require the writers to do an extensive amount of hand waving to avoid creating (another) contradiction in the continuity.

Take the NX-01 Enterprise's encounter with the Ferengi as an example of the level of contrivance needed under such circumstances: the name "Ferengi" couldn't be uttered in earshot of the crew, most of the crew never got a good look at them, and there wasn't much chance to take scans or make other records.

Answer 2

"Balance of Terror" establishes what Starfleet knows about the Romulans a decade after Discovery.

Captain's Log, stardate 1709.2. Patrolling outposts guarding the neutral zone between planets Romulus and Remus and the rest of the galaxy, received emergency call from outpost 4. The U.S.S. Enterprise is moving to investigate and assist.

[Corridor]

KIRK [OC]: This is the Captain speaking. In our next action, we can risk neither miscalculation nor error

[Bridge]

KIRK: By any man aboard. Listen carefully. Science Officer.

SPOCK: Referring to the map on your screens, you will note beyond the moving position of our vessel, a line of Earth outpost stations. Constructed on asteroids, they monitor the Neutral Zone established by treaty after the Earth-Romulan conflict a century ago.

[Sickbay]

SPOCK [OC]: As you may recall from your histories, this conflict was fought,

[Engineering]

SPOCK [OC]: By our standards today, with primitive atomic weapons and in primitive space vessels

[Bridge]

SPOCK: Which allowed no quarter, no captives. Nor was there even ship-to-ship visual communication. Therefore, no human, Romulan, or ally has ever seen the other. Earth believes the Romulans to be warlike, cruel, treacherous, and only the Romulans know what they think of Earth. The treaty, set by sub-space radio, established this Neutral Zone, entry into which by either side, would constitute an act of war. The treaty has been unbroken since that time. Captain.

KIRK: What you do not know and must be told is that my command orders on this subject are precise and inviolable. No act, no provocation

[Engineering]

KIRK [OC]: Will be considered sufficient reason to violate the zone. We may defend ourselves,

[Sickbay]

KIRK [OC]: But if necessary to avoid interspace war,

[Bridge]

KIRK: Both these outposts and this vessel will be considered expendable. Captain out.

So as far as starfleet knows, no ship has crossed the Neutral Zone in either direction for 100 years since the Romulan War. Apparently there has been no contacts by subspace radio since the war, either.

later:

KIRK: After a whole century, what will a Romulan ship look like, Mister Stiles? I doubt they'll radio and identify themselves.

STILES: You'll know, sir. They're painted like a giant bird-of-prey.

Stiles doesn't know that all Romulan ships will always be painted like a giant bird-of-prey. It turns out they still are in his time, but a century later in the time of TNG they are not. So Stiles was only guessing about that.

In in the era of Discovery, a decade earlier, if a ship crosses the Neutral Zone in either direction and is detected, a war will start that didn't start in the alternate universe of TOS. If the crew of Discovery have any Romulan contact they will be obligated to report it to Starfleet Command.

So I can imagine that crew members of Discovery might visit a busy spaceport on a new contacted planet and someone might point to a tentacled alien and say: "That's the weirdest alien I ever saw." and someone else might say: "It sure is. I wonder if it could be a Romulan."

And that is about all the writers of Discovery can do with Romulans.

Answer 3

The Romulans dont ascertain reappearance until the Federation's first encounter with them visually in 2266. (TOS: Balance of Terror) After the Earth Romulan War, the treaty and negotiations, neither side knew what the other looked like or ever faced them.

Presumably the writers Don't wish to incite canonical changes that dictate the original history.