I would like to see the MLB model adopted for basketball as well, but it would create additional complexities for both the NBA and schools as it would create havoc and uncertainty in recruitment. The signing period in basketball was from April 12, 2017 through May 17, 2017. The NBA draft will be held on June 22, 2017. Schools would be at risk of wasting a scholarship and roster spot on a player drafted by the NBA (my guess this would be a bigger issue for non-lottery picks) and the NBA would be at risk for wasting a pick on a player who decides to go to school instead.
Under the MLB model, the drafting team also loses its rights to the player who goes to school. Alex Rodriguez used the threat of enrollment at the University of Miami to force Seattle to up its signing bonus in '93. I would be amused to see powerhouse community/junior college teams being formed by players who did not like their contract offers and/or the team that drafted them going to community/junior college to reset their draft eligibility after only one year instead of three.