Dallas' move makes sense. I think people agree with the argument that they want to win now so that's why they're doing this but even from a long term perspective it makes sense because Dallas pretty much hedged all their future picks on winning now in the Kyrie trade, followed by PJ and Gafford.
They don't have any first from 2027 to 2030 and, not so coincidentally, Kyrie's contract is till 2026, by which time he'll be 36/37 so we'll past his prime. Even if they keep Luka, they won't have the assets to rebuild, the only hope would be in the free agent market and that's a separate bet because you can never be certain a big name will come to the franchise, they've gone through that heartbreak before. So Dallas I think came to the conclusion that even with Luka they can't win a title in the near future.
For the 'winning now', you can argue they just reached the Finals and became better with the acquisition of Klay and the further development of Lively/Hardy but I think there are a couple of things to consider. They lost defense in Derrick Jones Jr and, more importantly, the West is a lot stronger, especially OKC, is stronger. It's ironic that Dallas have beaten OKC multiple times this season without Luka but even if you consider the series they won last season, Luka really struggled under the defense of Dort and it was the others that stepped up. OKC have only further added to their backcourt defense with Caruso coming, so that would make it more difficult for Luka in that series. AD on the other hand would go against their bigs, which is the weaker part of their defense. Add to that having AD and Lively/Gafford would also match up well against Jokic. The East has also gotten better with the Knicks and Cavs looking like a viable contenders. I think last season Dallas would've beaten any East team other than the Celtics so you could say they were unlucky there.
So yea, Dallas didn't see a viable future so went further into the win now mode.
Lakers lose their chance to win another title this season with LeBron while Dallas lose their franchise player. I think the people happiest at this trade are the teams that have Dallas' future picks because Dallas will definitely go bust when those come around