so why is there no "A-list" roster for the US in the world cup tournament? Is it bc teams won't allow players to go? Is it because the players themselves don't want to? Is it arrogance? Did they just underestimate it all? I'm actually curious...
Because the world WANTS to see the NBA elite compete and win! (and I say that as a german basketball fan.)
USA Basketball can only select from players who make themselves available. The reasons why players would choose to make themselves unavailable range from a) they want to have a summer off; b) they have some injuries they are trying to get over, to preserve themselves for the coming NBA season (Jokic, Giannis); c) their club might have put pressure on them to not play (like Kristaps); or they don't see the World Cup as important enough to give up their summer; or e) they just don't care.
Having lived overseas in Sydney and London I found out how important representing your country is to non-US athletes and to fans - they see representing your country as the pinnacle. I observed how selections were made for Australian and English rugby and cricket teams, it was very clear to everyone - fans, players, clubs - that the national team was the ultimate. With soccer (including US soccer) they even have an international break in the Premier League and other national soccer competitions to accommodate international friendlies, so players can be released by clubs for selection. Even though players like Kane, Ronaldo, Messi, Neymar, etc were all getting paid millions by their clubs those clubs would never stand in their way when it came to representing their countries (though there was always frustration when someone had to fly halfway across the globe to play a "meaningless" friendly and then get injured).
Here in the US, at least with basketball, it's different. Historically there's not really been that hierarchy where USA Basketball is at the top, and they have first dibs on players. Players play for franchises in a closed system, the franchises really don't have an obligation to release players. They have been doing so since 1994 - prior to that it was all college players. I feel that the desire to represent their country isn't universal among players so they don't always make themselves available, especially if they've done it already (like Curry, Cryrie, LeBum, etc). They are willing to do it for a major competition like the Olympics, but these FIBA tournaments are seen as Mickey Mouse tournaments, and by fans as well. Players and fans feel that the caliber of the NBA overall is higher than any of these FIBA tournaments, including the Olympics, so a lot of fans don't really care, and it probably translates to how the players feel. The world may want to see the best NBA players compete, but a lot of US fans don't. Poll people here and I would guess at least 75% would either not care or not want Celtics players to risk injury playing in a "meaningless" tournament. When Tatum was selected for the Olympics last year there was a lot of concern from folks here that he would injure himself and be unavailable for the coming NBA season. This season he probably just decided he wanted a break but will probably make himself available for the Olympics next year in Paris, because that's only a 12 team competition vs this one being a 32 team one with a lot of dead rubbers.
Obviously every player is different - some take it seriously and want to represent their country, like Melo and Durant did. Others could care less. Others see the NBA season as more important. And if they opt out there will be very little fan or franchise pushback. So the reality is that Team USA will always have a relatively new roster for each competition. In Colangelo's time he tried to require a 3 year commitment for selection, because he recognized that the US was at a disadvantage in terms of chemistry compared to these international teams that have consistency of selection and have been together for years, but then nobody put their hand up, so they scrapped it.
If you compare basketball to soccer, the other global sport we play, we're obviously not the best at soccer, there's many countries that produce better players and there are better leagues, so a competition like the World Cup is considered the pinnacle. So our team has plenty to prove in mixing it up with the world's best. But in basketball the NBA is considered to be the pinnacle of the sport, above the Olympics and FIBA. That's why we call the NBA champion a "world champion" (which Noah Lyles hates
).