Fultz may not be a franchise player, but that's not what the Sixers need, with Embiid, Holmes, Simmons, Saric and RoCo, the glaring need was at guard. TLC was the only guard on the roster that could projected as a NBA starting quality player.
With Fultz, you've filled that need with a player with no obvious flaws, he can play PG, off guard, shoot the "3", and with BB breathing down his neck, has the size, reach and athleticism to be a plus defender. He may not be Westbrook or Harden, but he could be Paul or Wade. As GS showed, you need players that fit together more than just stars. Fultz is a great fit on this team.
And it's not like this trade stripped the Sixers of assets, they have 4 2nd rd picks this year, and 3 1st round picks and 6nd round picks (a number almost sure to end up between 31-40) the next two years. That's a lot of assets to pick, stash and wheel and deal to build depth. Oh yeah, they also have Korkmaz coming over in a year, the Turkish Korver.
What's not to like?