Yeah initial reaction is James Jones / Puppetmaster Sarver seem to have actually taken a W, Phoenix got the best of this trade. I can see why they were trying for Dillion Brooks instead for roster reasons, but Oubre is another talented forward to add to the heap. And while you think its a logjam at SF, keep in mind
1. Ariza's absence will provide a lot of minutes. He was the starter and played the most of all the wings.
2. Having a team full of 6'6"+ interchangable wing forwards is literally their plan, and has been the plan pretty much since the 3 pg thing died. Fired GM McDonough wanted to draft Shai and Sarver overruled him. So McDonough was gonna have the whole team at least 6'6/6'7 with Igor's Euro championship-winning motion offense and all mobile, switchable defenders, even the bigs. On paper seemed like a good plan for the modern NBA but apparently Sarver knew better.
Plus trading Ariza feels like literally no hit to Phoenix at all. Internally, the team had been discussing the possibility of an Ariza buy-out since the first week of the season. Not only are we on our first win streak without him, but he was actually pretty trash for the Suns all season, save a few standout games. But most of the time he looked really bad and it was odd how the tentative inexperience of the young players seemed to be contagious to Trevor. Rather than a calm and steadying presence on the team you'd expect from that "veteran leadership" intangible, the opposite occurred. Instead we saw Ariza make rookie-type mistakes all season - throw the ball to nobody out of bounds, airball wide open 3s, called for travel after a headfake - it was like he was possessed by the spirit of Dragan Bender. Plus he missed a good amount of games for "personal reasons" that were never explained. Seemed like he checked out early on. Im sure he'll be better in a more comfortable environment back in Wash, but he pretty much gave us nothing.
Ultimately Oubre is insurance, both in case of injury and also if a trade for a Jackson or a Warren may present itself. If he kills it then Im sure the Suns will make him a healthy offer to continue with the team going forward like they plan on doing with Richaun Holmes who's been very good backing up Ayton and even finishing a lot of games. Worse case scenario Oubre doesnt fit at all and they give him the Elfrid Payton sayonara and its exactly where they would have been with Ariza anyway.