I have used an odds-based CRT in two of my wargame designs, and the second one only counts if you consider Napgammon a wargame. The eternal and interminable question of what is a real wargame very much aside, one might wonder why that is: do I dislike odds-based CRTs or something? Well, no; I actually rather like them. I've played and enjoyed a number of games that trot out this oldest and warhorsiest of old warhorses. Heck, Mary and I have published such games.
So, no, I've got no beef with comparing the strength of the attacker to that of the defender and expressing it as a simple ratio. There are certainly some folks out there that do, that see them as a barrier to entry, as the reason why the hobby isn't growing (spoiler alert: it is growing) and why it's dying (it's not). I recently listened to a jeremiad from a wargames publisher about how there's no reason why any game should have an odds-based CRT in the year of our lord two-thousand and eighteen: custom dice, that's the ticket.
And I can't say that all those people are wrong, necessarily, because in our personal experience, the games that attract new gamers to wargaming often don't have odds-based CRTs. The games that really resonate with people, that serve as our flagship titles, usually don't have a CRT at all, odds-based or otherwise - they're more likely to utilize a "roll to hit a target number" method of combat resolution (when there is out-and-out kinetic combat in them at all). So, in a way, they're right: CRTs do provide a barrier to entry, and games without them do sell better.
At the same time, it's not like the concept is anathema to a huge swath of gamers. What you might call "core" wargamers - the folks who know the difference between a counter, a marker, and a chit - still have an appetite for them. And newbies do pick them up and give them a go, and every once in a while you get a convert. Purely from a business perspective, there's a market for them, and as long as there's a market, it makes sense to produce them. And I think there's going to be a market for them for a very long time; I think a lot of the earnest hand-wringing and doom-and-gloom prostignation that circles around discussions of hex-and-counter odds-based wargames - whether from folks who see them as an albatross around the hobby's neck, or from folks who think them an endangered species whose habitat must be protected against the encroachment of cards and wood bits - are a little silly.
That's just from a business perspective, though. And if Mary and I made our business decisions from a business perspective, we probably wouldn't be publishing print-on-demand wargames designed for a niche audience, and probably wouldn't have called a game Supply Lines of the American Revolution: The Northern Theater, 1775-1777. Whenever possible, our decisions are creative decisions, passion decisions. And from a creative perspective, from a designer's perspective, there's a lot about odds-based CRTs that recommend them.
For one thing - and I know this is going to sound weird after that preamble - odds-based CRTs make more games more accessible - at least, they do for folks who know how to use them. Once they've learned the ropes, calculating the odds and checking the table becomes second nature, almost a thing of muscle memory. They're familiar with it and it becomes that much easier to pick up new games, because they're not trying to learn yet another combat system. Now, getting over that initial hump can be a problem for new gamers, though I think it's not as onerous as it appears at first blush. (I would recommend that they not read the section of Dunnigan's book entitled "Overcoming Math Anxiety", which starts by instructing perspective players to count up all the combat factors on each side for each turn, and for me at least achieved the exact opposite effect of the section's stated purpose!)
Well, some of the naysayers might naysay, it sounds like you're saying that one of the appeals of odds-based CRTs is that they're all the same. I fail to see how that's something to recommend it from a creative perspective!
First, thank you for setting me up so nicely, fictional strawman. I have two possibly contradictory answers for that. First, sure, let's say that the vast majority of odds-based CRTs function roughly the same way. There's nothing necessarily wrong with that! I mean, the vast majority of movement rules in games work the same way - moving hex to contiguous hex, spending movement points to pay the terrain cost. Traditional mechanisms are like a mirepoix; they give you the flavor base that allows you to do more interesting things. Gamers can spend their bandwidth learning and concentrating on the things that are unique about the game. It's only a problem if there's nothing unique there, just as mirepoix is only a problem if all you're doing is serving up a few diced vegetables.
The other answer is, who says all odds-based CRTs work the same way? There's a lot you can do just with the numbers. Many games round fractions down, in favor of the defender. You've probably felt the frustration of piling together 20 factors against 7, and ending up with a two-to-one instead of the coveted three-to-one. This can of course lead to tedious and gamey factor-counting, but it also tells you something about the designer's view about how combat might intrinsically favor the defender. Some games opt to round fractions mathematically - not only will that 20 to 7 give you a three-to-one, but so will an 18 to 7 - and, paired with decent fog of war rules, it prevents factor-counting and stresses the importance of making decisions with limited information.
In my odds-based CRT game Von Moltke's Triumph, you have a situation where one side looks much better on paper than the other. The French had much better rifles and much better soldiers, but they absolutely got trounced by the Germans, who were using outdated weapons and fielding what was largely a conscript army. To reflect the "paper value" of the French, they rounded fractions up when attacking, while the Germans rounded fractions down. In the game, the Germans always win the war - though a good French player can "win" the game by not being quite as humiliated as poor Napoleon III - because their numbers, their staff work, and their offensive use of artillery proved more decisive. By rounding fractions differently for the two sides, I tried to impart some of that feeling of dissonance that the French must have felt as their armies were surrounded and forced to surrender.
These are the kind of things you can get across with something as subtle as what to do with the fractions. Never mind the great debate as to whether terrain should double the defender (acting as a literal force multiplier) or give them an advantageous column shift. Say we've got 10 factors to 3, and we're in "round fractions down" mode. Unmodified, we've got our 3:1. Terrain that imparts one leftward column shift brings it to a respectable 2:1, while terrain that doubles the defender makes it 10 to 6, and turns it into a 1:1. And this kind of seemingly ordinary decision can tell us something about the situation and the designer's read on it - it's chrome without the chrome.