Personally, I don't like this trade for all of these teams except Wizards. But If Milwaukee is really that interested on acquiring Lavine, then this is an ideal trade framework for them.
Why would the Kings even do this?
They're trying to get rid of Zach, and Bucks is like the only team interested in him. Keon doesn't play that much, and is bound for an extension, if they won't pay him, then it'll be better to trade him to get something in return.
They acquire Bobby, a scorer off the bench that brings toughness to this squad. Great vet, and could be a culture changer for a disgruntled team.
Why would the Bucks do this?
They don't give up anything valuable, EXCEPT Bobby.
They acquire a scorer that will help Giannis, and a 3&D in Keon.