If the Cs had kept IT and traded for another star, they assuredly would have had to trade at least the BKN pick (or the LAL/Sac pick) along with Crowder and AB. During the 2016 draft, I thought the Bulls were pushing for the '17 and '18 BKN picks in return for Butler.
It also would have prevented us from signing Hayward, which seems to be majorly overlooked here.
Going forward, we would have had a core of: IT, Butler, Horford with no '18 BKN pick. If Danny did not want to re-sign IT, then that core dwindles quite a bit, although we would then keep Smart.
Instead, we now have a core of: Irving, Hayward, and Horford with no '18 BKN pick. Along with Tatum, Brown, Rozier, and presumably Baynes (same as above), we also get to keep Smart and have added Marcus Morris.
I understand the reluctance to do this deal and even not necessarily loving Irving, but there is no doubt our core has gotten younger and looks better for the future. That extra year on Irving's contract may not seem like much, but the difference in keeping or losing Smart also matters a lot to people.