Personally, I think that the game has suffered at every level from that approach, because instead of increasing the fitness of the best players, coaches go with the best athletes, who might never have played basketball before. I'm not saying that the guys with skills are incredibly out of shape, but, and maybe this is just me, I'd much rather have skilled players; and when they get tired, guess what - that's what a bench is for. I know, what a radical concept (sarcasm).
It has but usually you don't see this past college.
The best players are skilled athletes. That has never changed. For all the talk of Bird, not being athletic, he had a computer mind and superior court vision and some of the best hand eye coordination of anyone who ever played. But he is not the norm. Being skilled is simply not enough if you do not have something else to couple it with. I have seen skilled kids who could shoot that can't create space and get blocked. An athlete who is just an athlete is just as bad but they tend to thrive on defense at least.
TP for the good insight. This goes back to what a local youth coach in my area absolutely preaches to everyone (1st graders all the way up to college)- The best players are in the best shape. All the athletes are in great shape more easily than others, and their fitness levels are more tangible for people. However, even Larry with his "white man ups" and amazing gifts alike worked his butt off during the offseason to get into shape with cardio and other physical aspects.
Folks, it's all of the above.
The less talented work on endurance. Perhaps the learning curve in specifically enhancing their skill set is too wide.
The more talented blend endurance training with peak performance of their specific skills and attributes. Then, blend the two groups of ppl together and you have a great team because the pure hustle player can give breaks to the skilled hustle player.
In the end, everyone does his part to flummox the opponent and make 'em work for every play and possession.
Psychologically speaking, that sort of team will dominate others, who're sitting around, waiting for the all stars to do their thing.