Why the blazers do it: they do it so get away from the tax, get a young prospect who fits their defensive identity, and most importantly, get off the last year of grants contract where they owe him 36 million.
Why Milawakee does it: they get a reliable secondary scorer, and a solid 1 on 1 defender for matchups like Brown/J Dub/Lebron Etc, addtionly, they add Ben Simmons to add more Ball handling, defense, and depth.