Reason against the Los Angeles Lakers signing Trevor Ariza: He is kind of redundant with this roster
Now, I did just say that Kyle Kuzma is the team’s likely main wing defender off the bench and that seemingly makes Ariza an even better signing. However, if the Lakers were to sign Ariza then they would be adding to a deep part of the roster rather than addressing any potential thin ones.
The Los Angeles Lakers are extremely deep at forward. Not only do they have LeBron James and Anthony Davis, but the bench forwards are deep as well. Kuzma, Markieff Morris and Talen Horton-Tucker are three solid rotation players and Montrezl Harrell will even play some four next to AD or Marc Gasol.
There are not many minutes to go around at the position, so adding Ariza could be simply adding to a logjam. Instead of Ariza, the team might be more inclined to address the point guard or center position.
Both positions are fine but it is easier to make the case for the Lakers getting another initiating point guard to play behind Dennis Schroder or even another traditional five as the only traditional five the team has is Marc Gasol.
You are not really addressing huge needs with the buyout market anyway, so it is easy to overlook this. But if the decision is between Ariza and either a point guard or center then it is easier, just from a roster construction standpoint, to sign said center or point guard.