You are right in saying that race craft is important, particularly at these World Championships in Yorkshire. I hope you have been able to watch some of the footage. Bolder (above) suggests that perhaps long, straight roads in most of the US are conducive to TT training, compared to Europe's hilly, narrow, curvy roads. More to the point perhaps is that those who have shone have done so because their experience is wider than that and they have proved themselves able to cope with roads and terrain that is very different from that. Quite apart from the necessary power output, wherever that comes from, is the need to ride the event with confidence and ability.
While I do not disagree with you, I'd add a bit of colour to the analysis with the US scene, because a lot of the time the scene is about crits and short stage races, and pack skills tend to be a less valuable commodity than they are in the European/WWT péloton; possibly a reflection that the very top names in the scene are usually pretty competitive in Europe, but the depth is a lot more limited so it's easier to stand out without needing to develop the same level of racecraft. Some of those who've come out of the NRC and been successful in Europe have never actually learnt that racecraft - Mara Abbott is the ultimate case in point; although she raced in Europe and on European teams repeatedly, she spent much of her seasons moonlighting in the NRC and seldom actually raced in Europe, so she never really learnt those pack skills or to overcome those deficiencies in her technical skills like descending, but her pure climbing strength meant that when the big mountains came, she could overcome that deficiency and then some. But she is the exception rather than the norm, and if you look at the convertability that Emma Pooley, who started out similarly lopsided in skillset, was able to show, you can still readily imagine that, had she been able to overcome her psychological hurdles and become a permanent fixture in the European péloton without losing any of her confidence, she could have had a much stronger palmarès than she eventually retired with.
The other rider in recent years to come from great success on the NRC to great success on the WWT is Coryn Rivera, who had primarily been dominating the North American crit circuit, but proved to be much more durable than her predicted niche as a sprinter would suggest. Others have required some time to adapt. Katie Hall obliterated the NRC last year, and it was definitely the right time for her to make it to Europe as she had nothing left to prove in North America, but to do so she's had to sacrifice a leadership role, and also learn to deal within a péloton where she isn't comfortably the best climber on any given day, which she has been in North America ever since Abbott's retirement - and indeed it's worth noting that her strongest results in the year have been the same races Mara used to do well in - those in North America and the Giro, where her pure climbing wattage is able to overcome any tactical naïveté or deficiencies in pack skills. Megan Guarnier took until her third year in Europe to really hit her stride, while Evelyn Stevens taking up the sport late meant that when she first got to Europe her technical skills were so underdeveloped at that point that she genuinely didn't know to have her inside pedal elevated when leaning into a corner when descending.
The question with Dygert will be how she would adapt to racing in Europe for several reasons, really. Firstly, because she has, like Hall last year, little left to prove in America. I'd assume she wants to stay track-focused for Tokyo, and rightly so, but after that it would be a shame if she continues to beat up on the NRC and not come to Europe to battle the Van der Breggens and Longo Borghinis of the world all year long. Secondly because if we only see her a couple of times a year racing against the top names, then these results will only ever be seen as anomalies and will be treated with perhaps more suspicion than they ought to be, with her being dismissed as a mayfly like Armstrong and Neben have been in recent years. Thirdly because if she only races against riders she can comfortably ride away from, she may never develop that tactical mind and achieve what she is capable of outside of the relatively limited North American calendar. And finally because the tendency for these American-based TT specialists to not race season-long against the best that the world has to offer, then turn up once or twice a year and beat them, deprives us of the rainbow jersey for much of the season in the Women's World Tour, and if the WWT is supposed to be a showcase of the very best and develop itself in the public conscience as that, then it would be a shame for the rainbow jersey to not be visible in the (admittedly too few) ITTs in the WWT. And also because it's also disappointing to watch riders, and get enthused by their exploits all season long, fighting for the WWT, then dismiss them all when we get to the World Championships - not only do we want the WWT to be a battle between the best to justify its role and position as the premier competition for women in the sport, but we as fans want to see the best battling against each other more than once or twice a season, and Dygert being hidden away from view in the mostly non-televised NRC makes it harder for us to develop the same attachment to her and interest in her progress that we have to other young prospects, as well as meaning we don't get to truly see what she would be capable of against the very best and stunting her road racing development.