WHY PISTONS
Though I believe Patrick Williams would be a good look for the Pistons (they need defense and they need a true PF like him), this is also a trade to free up their flexibility for trades. The Pistons need A LOT of change. Having their draft rights returned to them can give them all of the flexibility they need to get Cade Cunningham some immediate solid help. This may be a long shot but maybe the Pistons even dangle Jaden Ivey and a slew of picks for Monty Williams product Mikal Bridges.
WHY BULLS
This is a trade for a dynamic point guard that can truly take some pressure off of Wemby and pairs well with Devin Vassell. It doesn't interfere with the current timeline yet Lavine would be the best player on the roster (though Wemby's potential is through the firmament of heaven).
WHY KNICKS
Depth. The loss of Mitchell Robinson hurt the Knicks. Adding two centers and two SG/SFs who can easily replace anything RJ Barett does keeps them in win-now mode. Funny thing about the Knicks pick is that they won't see it anytime soon because the Pistons won't be winning unless they have the flexibility that those draft rights rob them of. They'll be in the lottery again this year with no real concrete end to a change in sight.
WHY BULLS
You replace Lavine with young talent with good potential, add depth, and most of all add picks INCLUDING (like the Pistons) gaining your draft rights back. Truthfully I think the dealbreaker here could potentially be Patrick Williams. Though he hasn't boomed yet, I'm not sure that they're ready to part ways. On the contrary, now with the rest of the talent they'd have left and the draft picks they're adding including their own, they could easily trade for another young talent like OG Anunoby and even go more veteran with it by acquiring Siakam. They'd have plenty of options and would be in play to continue improving the team every time there's a trade available to be made. My thoughts would be for them to actually pursue Dejonte Murray which is a much better fit with DeRozan than Lavine is.