As someone who rarely watches NBA games, I hate to see these "one-and-done" players come and go in only about five months' time. This benefits the NBA, with tons of free promotion of their new players. But this system is hurting college basketball, especially if you're not one of the few teams who get these elite but temporary players.
In football, you have to be three years out of high school to be eligible for the NFL draft. In baseball, if you go to college, you have to be 21 or have completed your junior year. Baseball also allows high school students to be drafted after graduation if they haven't attended college.
If basketball players had to commit to two or three college seasons, it would spread the wealth of talent and college basketball would see an immediate improvement. Right now, top schools like Duke, Kentucky, and Kansas can string together a series of similar recruits, one per year, over and over again. Kansas recruit Kelly Oubre reportedly said he picked Kansas for 2014 so he could replace current freshman Andrew Wiggins. That's great for Kansas but Oubre would likely have gone elsewhere if Wiggins was required to stay for two years. Then two schools would have had a great player for two years, instead of one school getting two players for one year each.
This year, 9 of the top 12 recruits (according to Rivals.com) were divided between just three schools and it's shaping up the same way for next year (with three to Duke, two to Kansas, two to Kentucky, etc.). Only a very small fraction of college basketball is benefiting from this talent as things are organized now.
And the NBA doesn't really benefit immediately either. Last year, 10 one-and-done freshmen declared for the draft. Only 8 got drafted, only 6 have played so far this season, and only two have started a game. It's widely discussed that most NBA teams seem to draft for potential rather than developed skill. For every NBA star that came right out of high school or one year of college, there are countless dozens who would have benefitted from staying at the college level another year or two.
Bottom line, this guy [see below] should still be playing at Kansas.