One goal would be to keep a foreign player in the draft, but Giannis was probably going to stay anyway.
Another I guess is to try to get the player to shut down workouts with other teams.
The downside is that the team that makes the promise reveals their hand and another team that wants that player can try to trade above the first team.
How binding are these "promises" though? Could Milwaukee 'promise' Larkin in order to try to force the Jazz to take him at #14 and leave another player they want at #15?
I'd be very surprised if they're contractually legally binding.. but rather political suicide for not executing on the promise (with agents, other teams.. etc.).
I'm sure there must be better reasons than I've thought of... so I'm going to find out.