I and I suspect the front office would have preferred to somewhat re-build, if they could have gotten a concrete building block as the centerpiece of the package (Brown, Ingram and I don't think they wanted Fultz, but maybe if he could have been re-routed for Jackson, etc.).
No matter how appealing they might have the potential to be 1-2 years in advance, straight picks for a star, much less a superstar, are too risky. Too much unknown, especially that far out. I realize there's a good chance a few end up top 5-10 (in a supposedly weak draft), but look no further than the past 5 drafts to find out how meaningless that could be (Len, Noel, McLeMore, Burke, Exum, Stauskas, Vonleh, Okafor, Hezonja, Mudiay, Johnson, Kaminsky, Bender, Chriss).
Flawed as he is, the odds of even landing a player as good as DeRozan are slim. Sure, he caps the ceiling relatively low, but if 3-5 years down the line those picks became the players I mentioned, how bad would it look to have traded Leonard for essentially nothing?
Aldridge-DeRozan become virtual expiring's in a year. If this (bridge?) era fails to meet modest expectations, they could shop both by the '20 deadline, recoup some (albeit lesser) picks/prospects and enter a re-build then.