If Ainge really wanted Kawhi, he could've turned the non-SAC draft assets alone into [insert comparable player to Derozan or unfulfilled/attractive prospect (Kemba, Aaron Gordon, Jabari Parker, Wiggins (admittedly there aren't that many at the moment))] in a 3-4 team trade. There are several packages that could be put together that rival the Derozan package using those picks, but it would've necessitated that 3rd team, which would've been complicated.
Kawhi or no Kawhi, this is a perrenial Championship contender and Danny is treating it as such. Of course we could've taken the same gamble that Toronto took, but unlike Kyrie, Kawhi's stated his intentions and if he leaves next off season was it worth it?
There's no need for a last hurrah move like trading 2-3 lottery picks and an important rotation player for a season rental because the ceiling of this team is multiple Championships.