I think what I would say is that if the star players feel as though they shouldnt have to play out a multi-year deal with a team they don't want to be on, then the teams should be able to cut players who are hurt or underperforming without taking a cap hit or having to pay the remainder.
Can't have it both ways. You want the security of multiple years guaranteed, you can't expect to have the freedom to insist that the team send you somewhere that you like better when there are multiple years remaining on your deal.
But they do have to play out the contract, unless the team trades them. The teams do not have to trade the player, they do it so they can get some assets when the player tells them he will not resign. They could hold on to the player, make him honor the contract, and then get nothing when he signs with another team as a free agent.
There's a difference between telling the team that you don't plan to re-sign versus telling the team you want a trade and having your agent do everything he can to force your team's hand to trade you to the exact place you want to go.
Between Kawhi, AD, and Paul George, it seems we're seeing a lot more players who are doing what they can to force their team to trade them.
I don't have a problem with players privately telling the team they are planning to go elsewhere in FA, as long as they continue to work hard for the team as long as they're on it. Certainly it's better than what a certain somebody did, i.e. state publicly that he plans to stay, then totally change course without making a clear indication to the team of his intentions, while noticeably checking out emotionally and in terms of effort, before ghosting the team once the season is over.
I think the ideal would be that the player and their agent have a running dialogue with the front office so everybody is on the same page. But you don't make public the fact that you're planning on leaving or that you've demanded a trade. That actively forces the team's hand and also sabotages the team's leverage for executing a deal.
I honestly don't know how the league is supposed to enforce this stuff though. You can't really use rules to eliminate leaks from agents to the press (or GMs to the press, for that matter). You can't prevent the players from talking to one another. The players and their agents are going to scheme to engineer the situations they want. I think we're going to see more and more players do what Paul George did, which is demand a trade even though they have several years remaining on their deal. We'll also see more players do what Kawhi did, i.e. effectively sit out almost an entire season.
I don't see a way to fix the behavior, so I would say that the teams ought to get something in return -- you want to renege on your obligation to give a good faith effort for the team while you're under contract? You want to have agency to choose wherever you play because you're a star? Fine ... get rid of fully guaranteed long term deals, then.
If stars want to be able to do what Paul George, Kawhi, AD, etc did, then they shouldn't be able to do what John Wall is doing right now, i.e. collecting a huge check for multiple years despite not being able to play at anywhere near the level he could when the deal was signed.