Why Memphis Do This. They may not trust Ja or JJJ to be the number 1 option on a championship team. Although KD might not be seen as that league-wide and is getting older. KD is still a top 10 player in the league when he's on the court and the depth that Memphis have would allow him to be at his best come playoff time while sharing the load with Ja and JJJ.
Why the Suns do this? The Suns do this to try and contend and gain some future assets to hedge their bets on Devin Booker's happiness. If Lauri returns to last season's form Suns can become a middling playoff Team while angling for another superstar down the line.
Why the Jazz do this? The Jazz get crazy value for Lauri including t an all star level talent in Desmond Bane who can be traded for more assets down the line or can be a running mate for their incoming rookies.
Why do does the Lakers do this? Get good value for the 2031 pick and the Kleber contract in a playoff-level backup C in Brandon Clarke who has quietly been one of the better roll men in the league. If Jaxon Hayes wants more than the minimum I could see themm be interested in a trade like this and also trading for a guy like Claxton or Poeltl.
Why the Magic do this? Bane could be the Magic's best bet to have an all-star-level primary ball handler. According to CraftedNBA Bane is in the 83rd percentile in passer rating and in the 94th percentile in creation. Bane also offers better defence than other options for Orlando, such as Anfernee Simons and Trae Young. They also get Grayson Allen who can drain a couple of 3s come playoff time.