The "series Gene Roddenberry created" was under constant revision in it's first season, with the characters and concepts evolving. Some ideas, like UESPA and the Enterprise being an Earth ship, were tossed aside in favor of Starfleet and United Federation of Planets. The UESPA was pretty much retconned away till Voyager brought it back.
I wasn't a VOY viewer either, and never realized UESPA was ever used outside of those early TOS references.
The sad thing is, I think many of the things on uniderth 's list above are the very reason they came up with Enterprise in the first place. They wanted to do a Star Trek where none of the usual rules apply. But from what I gather, during development the suits at UPN kept insisting that it be more like Voyager or TNG, ie that it be more instantly recognisable as Star Trek right out of the gate. So ideas like using normal weapons was vetoed in favor of "phase pistols", simply because UPN thought audiences expected Star Trek to have phasers; and ideas that were thrown around like having Archer and co on Earth dealing with the foundation of the Federation were axed because the suits thought there needed to be a Starship and "strange new worlds". So all the really sensible and interesting new stuff that a prequel to TOS might reasonably be able to do was kind of fudged, in favor of finding a middle ground closer to what the suits thought Star Trek 'is'.
Add to that phasers replacing the lasers of "The Cage", not by technological upgrade but by retcon - lasers being a real-world technology couldn't do the magical things the writers of TOS wanted, so they simply altered the name. It's all in The Making of Star Trek.
I guess I am totally missing something here. If the crew of NX-01 knew of the plague and why there were now smooth forehead Klingons, how come in 2373/2268 Bashir,Odo and O'Brien asked Wolf "those are Klingons"?? in the episode "Trials and Tribble-ations"??
Because the people who did the two ENT episodes about this didn't seem to understand that they spoiled the joke.
I've had issues with this myself. Admittedly, Bashir doesn't know anything about history in the episode, and O'Brien, the apparent expert, doesn't even know what Kirk looks like. Worf, of course, knows all about it, and I'm sure Dax (and probably Sisko) would know too. Odo, as a Changeling raised on Bajor, understandably doesn't need to know anything about Federation and Klingon history, outside of what he's picked up for mission briefings. Bashir *should* know though, just as the basics for a doctor who operates on Klingons. And, arguably, everyone in the Federation should learn in primary school that some Klingons spent 100 years looking like humans, due to the most important virus in galactic history. Klingons seem to be history revisionists, so I have no problem with them removing the entire augment virus era from their recorded history. Alternatively, the virus' origins could be covered up, perhaps for political purposes, but its effects could not be.
I think ENT did a fine job explaining the difference, and I totally accept it. I don't see what the big deal is. Yeah, sure, maybe Bashir should have known about the change, but the writers of "Affliction" and "Divergence" shouldn't feel hampered by dramatic restrictions like that. If they want to tell a particular story, LET them.
The change from smooth back to lumpy presumably happened between TOS TV and TOS movies. During this period Kronos was still at odds with the Federation. Klingons are cagey at the best of times, so the Federation wouldn't have known what was going on (unless Section 31 had deep-cover agents in the Empire). Eventually, after peace was made, the truth might have been made public, but by that time it wouldn't have been "news" as such. For students of history, the origins of the plague might have been of interest, but as it doesn't seem to have any effect on Klingon-Federation relations it would be relegated to the social history category. It might be of interest to scientists engaged in genetic augmentation research, but that would be a rather limited number of people (especially given how controversial the subject is). There would be no need for general medical practitioners to be aware of it, as it has no current medical relevance (as far as we know).
How many of us know what Chet Nimitz looked like? I mean, without googling? Could we tell him apart from, say, Spruance? Or Halsey, whose face arguably is the most distinct one of the lot? Even those considering themselves naval history buffs might have trouble there. TOS uniforms make it difficult to identify a person's rank or position. Unless O'Brien has a clear line of sight to the sleeve cuffs, and remembers how those worked more than a century ago, the error is pretty realistic. How so? The only thing it ever really affected was making it easier for Arne Darvin to pretend to be human. Timo Saloniemi
Or, much like Bashir not knowing that the colour-code for uniforms were different in the TOS era to the DS9 era or that the women wore short skirts - it just wasn't something they knew about in history.
Because someone who studied inter-species medicine and was capable of treating and operating on Klingons would know that. .
We saw that Section 31 was involved in the Affliction/Divergence arc. Maybe they covered the whole thing up afterward. Sure seems like something they'd do.
Actually, the viral explanation is a pretty lousy one. In an era where surgical cosmetic alteration can be achieved relatively easily; what Klingon would be dishonored by looking like a human? If I was a Klingon and I was infected the first thing I would do is get my ridged surgically replaced. So there is pretty much zero change that Kor, Kang, Koloth would be smooth headed in Kirk's-era. So no, this so-called "Augment Virus" does not explain human looking Klingons.