Well said. From what I've read on this thread it sounds like people have tried everything to change this behavior and nothing has impacted it at all. Which says to me it must be a programming issue (that could potentially be fixed by Mazda or a company like JBR via an aftermarket tune). You hit the nail on the head regarding why owners are so frustrated. If Mazda would simply explain why this is happening or even just acknowledge that it's real people would be a lot happier. One of the more interesting aspects of this is that it's not more widely mentioned. Other than Savagegeese and this thread I haven't really come across anything mentioning it. None of the industry reviews mention anything about it ever which is fairly strange. Even stranger is that you'd think that one of the dozens of YouTube reviews would have encountered this. I've personally seen at least a handful of cold weather reviews and everyone raves about the added turbo power and traction in the snow but I haven't heard anyone mention a total lack of boost in 1st and 2nd gear. I have heard people say that they don't really feel the turbo as much off the line but most attribute this to lag. Just weird that none of the testers have noticed this.I think people have tried TCS off and it didn't change the behaviour.
Earlier in this thread I speculated that maybe Mazda does this because all-season rubber starts to get harder at temps below 44F, and 20F is the limit they decided on because that's when road salt starts to become less effective. No idea if that's true, but in the end, Mazda's reasoning is likely a combination of the many theories that have been put forward in this thread. They just won't acknowledge it or confirm it, which is annoying to say the least.
Regarding your last statement, those who are complaining about the issue don't really care whether they will have traction or not, or whether they'll hit a black ice patch. What they do care about is the fact that they bought (or are paying for) a car that advertises peak torque of 310-320 lb-ft at just over 2k RPM, but they don't get that when it's cold out, and Mazda isn't telling them why.
I cannot personally attest to this as I haven't gotten my CE Turbo AWD yet (should arrive on the 12/27 and I'm counting the days!). I currently have a a 2016 CX5 with the NA 2.5 and I have not ever noticed any change in acceleration whether it's super cold or super hot.
In summary, we seem to be well past the point of trying to come up with settings that can be changed on the driver's end of things to fix this or debating whether this is a real thing. Many reliable owners have said they absolutely notice this consistently and there don't seem to be many left who are claiming that they've never experienced it or that it's only an occasional problem. I think the best course of action would be to all pester Mazda corporate about this and hope that they finally do something.