As when Elway manipulated his way out of being taken by the Colts, or Kobe manipulated his way to being selected by the Lakers, or people like Shaq (AD, Kyrie, Leonard...) dump their teams to seek greener pastures, these things happen in a pro sports world that no longer treats players as indentured servants playing at the service of whoever "owns their rights".
The cost for this freedom is (IMO) that their are unfair advantages for teams in better locations or for teams that can spend more money (baseball: NYY, Red Sox). Obviously, through good fortune and wise decisions, teams can overcome location or $$ disadvantages (Patriots, GSW, Toronto, San Antonio). But the usual suspects (Lakers) will rise quicker and in some cases will rise even in the midst of dysfunctional management (Lakers).
That AD can drive the train -- essentially determine where he'll play -- is (and should be) his right, but that definitely influences fairness which seems pretty important in a competitive league. There ABSOLUTELY should be team compensation when a player blatantly manipulates his way to the team of his choice or when a player like Kyrie decides to leave team high and dry. If the C's knew there would be some compensation on the other end if AD were to leave after a year, they very well may have made a deal with the Pels. Pels would also have been in a better position to drive ther price up (as they should be able to do) for their franchise player. And the Lakers wouldn't have once again gotten the top 5 player to go along with their existing top 5 player -- who they stole from Cleveland with no compensation a year ago. Free agency is a player's right and in the NBA the hope was that being able to pay them more would reduce team abandonment, but it's not enough. Nets should have some mandatory compensation for the C's when they sign KI, just as the C's should have compensated Utah and Atlanta for GH and AH signings.