Warriors Golden state do this because they get a dominant young Center in Mitchell Robinson who can fit in nicely and help the team win NOW. They also get rid of a problematic Draymond Green who has been causing locker room problems for them this season. James Wiseman who has been predominantly playing in the G-League this year however still has a lot of potential being the second overall pick. So to gain a solid role player in cam reddish a streaky shooter in Evan Fournier and a franchise center in Mitchell Robinson I say the warriors come out pleased with this move.
Knicks New York do this trade to solidify there bench with a solid back up center to play small ball with in Draymond Green that suits there back up center position better than a hartenstien or a sims. With the Knicks not being in a win now position and being a relatively young team in relives the pressure from James Wiseman to impact immediately they can develop him as well as they did a Mitchell Robinson while wiseman also has the higher ceiling. They also get off fourniers horrible contract. I think this is a move for the future for the Knicks but I think down the line this trade will better the team.