Ideally it needs to be a balance. You build a program with "program" guys who stay four years. You supplement with the superstars who can drive a team to the next level. (See Syracuse Orange 2003.) With the growing prevalence of the one and done culture it is essential to fill all 13 spots with potential contributors, particularly in a system like ours that is by no means plug and play. This is key and borne out by this year's struggles IMO.
Having capable pieces, even if they are stop gap solutions while a talented freshman learns the ropes makes transition periods easier to navigate when there are unexpected departures. As the NBA moves toward its stated goal of 30 for 30 with one D-League team for each NBA team this will become even more challenging. While as fans we see D-league as a step down from high major college ball, this is becoming more and more the prevalent route to the NBA and the relatively small salaries in the D-League seem irrelevant to many of us, it's more than a player makes at any college (with the possible exception of Kentucky), and a high paying job for many of these kids from low income households.