Cooper just wasn't living up to his cost and wasn't working out. He checked out of too many games when he was needed most. He was basically quiet, but he was passively a diva, high maintenance ego guy and sulked when he wasn't getting lubed enough. They needed to get out from under his deal while they could. Nobody was offering more than Cleveland, though they might have played it better and started dangling him earlier and more effectively. They still weren't going to get a heck of a lot more.
After the airport thing, fuck Odell. But he would have been a short term guy at a reasonable price to throw down with the extra cap space they have. They don't need a star or a superstar salary. They need another decent receiver that can draw some kind of attention and make some catches when it counts.
Look back at all of those WTF decisions people were ranting about, and most of them proved to work out just fine. The O-line has jelled, rookie left tackle has stepped up, we don't miss Collins, who has been fighting injuries all year. We don't miss Gregory in the least, in fact Dallas upgraded the pass rush with the guys they already had. They didn't need to throw big money at an aging linebacker. A DB would have been nice, but there really wasn't one there.