I'm perfectly fine not getting Ariza. He is overrated, and slightly overpaid. I don't think he would fit in to this teams future very well.
Not to mention, the C's didn't have a Courtney Lee to trade. Don't sleep on him, he is a very nice piece, and the kind of guy who has slipped under the radar that Houston has targeted over the years. I don't think the C's could have competed with this deal.