Once again, instead of telling others to open their mind and look at new perspective, YOU are the one who needs to realize that you're looking at this extremely narrow-mindedly.
Don't do this Brooklyn trade? Uh oh, we get Josh Smith. Now we're stuck being average!
Don't do this Brooklyn trade? First round exit next year. Now we're stuck being average!
Don't do this Brooklyn trade? KG/PP retire and we get nothing. Now we're stuck being average!
You know what though? That's not true. Who says we have to get Josh Smith? Who says you can't rebuild while being a playoff team? Who says we can't trade KG and/or PP to other teams where we would undeniably get a better haul than this one? Who says we wouldn't benefit more simply from the cap space from KG's and/or PP's retirement?
You know what, you're right. Some people really don't get it at all 
In addition, I also see you frequently say that there are no other options. Many of the rumors we've heard are indeed that, rumors. The Warriors simply inquired about KG. We have no idea what they offered, if they offered anything at all.
But what about a Cleveland? I don't think that ever got to serious talks because Ainge thinks it was a lowball offer, but two early second rounders in this year's draft plus a sizable trade exception? I'll take that over having to take back Gerald Wallace every day of the week.
And what about the Clippers? I was already a huge dissident of that trade. I'm not a fan of Deandre Jordan's at all, and to pay him his ridiculous eight digit salary, PLUS his trade kicker, was an awful proposition in my opinion. BUT, compared to the Brooklyn trade, I'd still take that awful Clippers trade every day of the week. Two years of an athletic, young center OR three years of an old, washed up forward whose game depended entirely on his athleticism?
I mean, these aren't even close. Keep in mind that in both of these trades, it meant letting go of only either KG or PP. That means we could've gotten even further assets than what we would've received in the mentioned trades. If Ainge were simply patient enough to test out the market, who's to say another contender wouldn't be interested? PP and KG are old, but still very productive and at a very cheap bargain.
Again, the fact that Ainge was impatient and stuck to this Brooklyn deal is awful. And again, you need to open your mind and not be so narrow-minded on your opinions. Rebuilding isn't simply something you can only do one way. There are many ways, and Ainge went with one of the worst ones.