If we got some of those players people think are one and done, I suspect the criticism of the squid would die down significantly. Some of those kids didn't want to go to college and would have gone straight to the NBA. That option was taken away from them. Even if the assumption that they are terrible students is correct, you can't blame them because they didn't want to be students in the first place. Why would you expect them to do any more than the bare minimum required?
And no, playing in Europe or overseas isn't a better option because they wouldn't be playing against better competition. The international presence is growing in the NBA, but until more players in one specific foreign league are drafted than out of college here in the states, they're better off playing here.
The criticism for the one and done situation belongs with the NBA, not the players or coaches. The players are forced into college, and the coaches want the best talent they can get to help them win.