So the reigning NBA champion, who is tearing it up right now and has shown no signs of slowing down, is going to give us their second best scorer, one of the best 2-way guards in the league AND their starting small forward who is yet to enter his prime for a 2nd-year guard who isn't quite ready for primetime, a rotation big (which they have plenty of), our back-up wing who isn't part of the long-term plan, and one of our picks who, if this deal was made, would probably be in the twenties. Take Thompson out of the deal and Golden State would still laugh.
The other deal is more fair, but why would the Celtics want Iguodala? Is he a pure wing and a good playmaker? Yes he is and I agree he would help, but his skills are diminishing and at this point is best served as a back-up playmaker/6th man like Golden State is using him now. Besides, the Celtics already have one of those. Isaiah Thomas, and on some nights, Evan Turner.
When you have a young team that looks like it's going to start a potential dynasty with the roster it has, you don't have to do anything drastic unless its for an upgrade (For example, I see Golden State being a darkhorse contender for Kevin Durant and that would cost them Barnes). In this case, there is no upgrade really in either deal for Golden State. They would get young talent but they already have plenty of that as it is. They also have all the leverage because Barnes is going to be a restricted free agent this summer. I know some have said the Dubs don't want to overpay Barnes, and I'm sure they don't, but they can, and since Barnes is only 23, they probably will. I'm sure OKC didn't want to pay Enes Kanter 4 years, $70 million, but they waited until someone else offered him that to give it to him. Unless the Warriors get someone better, I think Barnes is going to stay put, especially since the salary cap is going to skyrocket, and hence, the luxury tax won't be nearly as heavy.
Also the 2015 draft has already passed. All future picks are 2016 and onward.