Mechanics-wise, they would be deadlier under D&D5E rules.
Philosophy-wise, Tucker's Kobolds have always depended upon DM fiat.
Two points before beginning:
- It is my belief that a fair amount of the "player's reactions to the kobolds" is viewed through nostalgia from when Roger Moore was younger, or embellished for greater effect, but that's just my opinion.
- When I say "DM fiat" below, I mean the DM making a rules call in a situation not covered by the rules. This is not intended negatively -- it is also my opinion that slavish adherence to rules-as-written is bad, that rule-of-cool is good, and that imagination should be rewarded. But it does need to be understood that this is all up to the DM and has no relation to the game system.
But let's do mechanics first, as it's simpler. Moore states that this happened during his time at Fort Bragg, which would put it between 1977 and 1980. It is unclear if the game being run is one of the D&D versions or AD&D first edition, but it doesn't make much of a difference. I'll go with AD&D1E for simplicity.
In AD&D1E, a kobold has 1-4 hit points (avg 2.5), a THAC0 of 20, 1-6 damage, and an AC of 7. In D&D5E terms, that translates to...
|Damage per round (AC 15)
|Damage per round (AC 20)
*: AD&D1E did not have any official rules for a critical hit, so there is no bonus damage on a 20.
**: Not including the D&D5E's kobold pack tactics, which would significantly raise this number.
(Now, fighters are not really comparable, given that the D&D5E fighter has a wide selection of feats, subclasses, etc to modify themselves with. The D&D5E fighter has more hit points, but not twice as many more, comparable AC, and comparable attack bonuses. However, this trip down memory lane did remind me that a 10th level AD&D1E fighter got 3 attacks every 2 rounds -- 1 on odds, 2 on evens -- but would get 10 melee attacks a round against kobolds.)
As you can see, in a straight stand up fight, the D&D5E kobolds have it better, even before accounting for pack tactics. Against an AC 20 fighter, it would still take a very large number of them, but way, way fewer than converted AD&D1E kobolds. If a DM were to make all the same rulings as the original, the encounter would be deadlier, but D&D5E contradicts several of those rulings.
But actually, that's all besides the point.
Tucker's Kobolds relied on the philosophy of DM fiat -- near everything mentioned in the editorial was based on DM rulings rather than actual calls and that was the philosophy of the game. Today there's a lot more weight given to rules-as-written , and D&D5E covers a lot more of this in the rules.
Let's review (all quotes taken from the PDF linked in the question).
The kobolds caught us about 60 feet into the dungeon and locked the door behind us and barred it.
Ok so far, though depending upon the group, it may have been the modus operandi to use iron stakes to keep doors from being closed behind them.
Then they set the corridor on fire, while we were still in it.
Unclear how the corridor was set on fire -- burning oil, maybe? It's my assumption that this is something along the lines of "pour burning oil into the entire corridor", or "pour oil into the entire corridor and then light it with a single flaming arrow." The burning oil of D&D5E is for a single target and requires two attacks to hit (one for the oil, one to light it), so that's obviously not it. DM fiat on how this works and what damage it does.
only to be ambushed by more kobolds firing light crossbows through murder holes in the walls and ceilings.
My opinion is that the DM at the time may have ruled that you simply could not fire back through an arrow slit or murder hole (there were no cover rules, so DM fiat); if it was allowed, it would probably be at -8 or more. In D&D5E, arrows slits are three quarters cover and so a +5 bonus to AC, which would still have a 10th level character hitting more than 50% of the time.
Kobolds with metal armor and shields flung Molotov cocktails at us
In D&D5E, molotov cocktails are probably close to alchemist's fire; being an improved weapon, the kobolds would probably be worse off using these than just shooting more crossbows. Especially if the characters were already on fire from the corridor being set on fire.
from the other sides of huge piles of flaming debris, which other kobolds pushed ahead of their formation using long metal poles like broomsticks
Seems obvious that the debris is to keep the PCs from reaching the kobolds. I doubt that the molotov cocktail throwing kobolds were given any penalties to attack because "they're area weapons" -- again, DM fiat. Getting over the obstacle would be ruled as difficult, but in D&D5E an 8 ft obstacle would be cleared by a fighter with 20 strength, and above that an athletics roll might be allowed to clear a taller one.
We abandoned most of our carried items and donkeys to speed our flight
DM fiat or Roger Moore's embellishment. Assuming you're not encumbered to begin with, abandoning carried items gives no speed bonus in any edition.
we were cut off by kobold snipers who could split-move and fire, ducking back behind stones and corners after launching steel-tipped bolts and arrows, javelins, hand axes, and more flaming oil bottles
DM fiat. Split-move and fire was not in the rules until the spring attack feat in D&D3E. I also highly doubt the players were ever allowed to make use of such a tactic even though the kobolds were. In D&D5E, split-move is standard, but this sort of behavior is specifically countered with the Ready action.
I recall we had a 12th-level magic-user with us, and we asked him to throw a spell or something. "Blast 'em!" we yelled as we ran. "Fireball 'em! Get those little @#+$%*&!!"
"What, in these narrow corridors?" he yelled back. "You want I should burn us all up instead of them?"
Although a legitimate concern in AD&D1E (a constrained fireball would expand to fill its 33,000 cubic feet of volume), a D&D5E fireball does not expand to fill its entire volume -- it only hits things with 20' of its center, so would not have this problem. But do note that there is no DM fiat helping the players here -- no "cast it over the piles of flaming debris and then hide behind them", no "cast it through an arrow slit and then cover the slit with a shield", no "cast it around a corner and then run", etc. Had the kobolds had a wand of fireballs, I'm certain the DM would've allowed them to do something along those lines.
Lack Of Player Preparedness
This is what makes me doubt the essential nature of the story the most. The players know that the kobolds are there and what they are like ("The party leader went over the penciled map of the dungeon and tried to find ways to avoid the little critters, but it was not possible") but there are no actual preparations that the players take other than "The group resigned itself to making a run for it." That's not how players in my experience work, ever. There is (at least) a 10th level magic user, but there is no dig to get around them, no invisibility, 10' radius or protection from normal missiles to avoid attacks, no stinking cloud or sleep (each use of this 1st level spell would get an average of 10 of them) to incapacitate them, etc etc. And that's not even counting what a cleric, with their more defensive magic, could provide.
Given the dread shown by the party in the story (""We still have to go out the way we came in," he said as he gloomily prepared to divide up the treasure"), I would imagine a group would simply make an expedition with the express purpose of destroying the kobolds and then worry about the rest of the dungeon. Dig or passwall into their tunnels to bypass their murder corridors and get it over with once and for all.
Low level D&D5E monsters are more dangerous than low level AD&D1E monsters (and kobolds especially, with pack tactics). But the moral of the Tucker's Kobold story was always "don't let your monsters being boring slabs of meat, think outside the box" and "think outside the box" inevitably meant "make DM fiat calls about things." Of the points listed in the question, where D&D5E addresses them (cover, area of attack spells, etc) it is universally to make them more balanced, which works against the kobolds.
We like Tucker's Kobolds because they're the underdogs, and we root for them. We like hearing about the plucky underdog monsters who defeat the big bad adventurers due to their cunning and tactics, and that's what makes Tucker's Kobolds a great story. But the exact story itself only worked because the DM wanted it to, and it doesn't hold up in later editions because it turns out that most of the rules calls made weren't balanced (and so PCs couldn't be allowed to (ab)use them in turn).