Why the Raptors do it:
They create a defensive super team that can switch on everything and give a team like Brooklyn hell in a playoff series, while also adding a tertiary scoring option / ball-handler in Oladipo, and you just hope you can convince him to re-sign and he bounces back to form, while also adding a veteran grinder like Tucker who can play small ball 4 or 5 in certain scenarios and provide spacing with bulldog like rebounding and defense. Lowry, FVV, Dipo, Tucker, Siakam, Boucher, OG is insanely good defensively and they can score, that team is sneaky problematic in a 7 game series.
Why the Rockets do it:
There's going to be a couple of 2nd round picks attached here, as well as a protected 1st, plus they get a nice young guard in Powell who they can showcase and potentially flip again for something else. Probably can send Baynes out of town for an exception or something as well. It's been no secret they've wanted to acquire draft capitol and shed cap space, they can do that here.
Why the Mavericks do it:
Dallas adds a young, dynamic, hybrid forward who can become a tertiary offensive weapon behind Luka and KP, and gives them that explosive athlete they've been missing forever. He's also an excellent defensive talent, which is something they lack. He not only makes them better now, but he fits well into their timeline moving forward. KP transitions to the 5 full-time, where he's had his nest success as a pro, and Gordon is cemented at the 4, where he's had his best results as well.
Why the Magic do it:
They add a couple of intriguing young point guards, which has been an area of dire need in Orlando for a long time, and they clear out some cap space with Johnson's expiring contract, so they can use that to reposition some other areas of need in the off-season / put it towards a Fournier extension as he's set to expire. Mavs are also adding a protected 1st round pick and a 2nd. Brunson would really thrive as the lead guard on a team like Orlando where they just need a guy who can create and go out and get a bucket, and then you add in Tyrell Terry as an interesting prospect to develop as well. Orlando has flirted with moving Gordon for some time now anyways, and Isaac is their long-term 4 anyways once he returns from his knee injury, they also have Chuma Okeke (1st round pick in 2019) who is slated to see time their as well, so a Gordon trade is ultimately a matter of when and not if.