He has demanded to be traded
The Redskins have already fulfilled their part of the bargain by paying Albert Haynesworth. Now, he has demanded a trade, after making off with a $21 million bonus in April. There is nothing else the organization can do to satisfy this man.
He refuses to play in a 3-4 defense
Haynesworth has made it clear that he has no desire to play in a 3-4 defensive scheme, regardless of the position. He wants "freedom to make plays," according to him, and the 3-4 won't allow him to do that. In other words, he wants individual glory, not what is best and most successful for the team.
The Redskins need to make an example of him
Mike Shanahan and Bruce Allen are changing the entire culture of the Redskins organization. Part of that process is making players realize that there will no longer be players who are "above" the team, and the same set of standards will be used for all players.
Mike Shanahan doesn't like him
You can see the contempt in Shanahan's face whenever Haynesworth's name is mentioned. Players like Haynesworth go against everything Shanahan stands for, and once a player gets on his bad side, there is no going back.
He has embarrassed Dan Snyder
Daniel Snyder was ecstatic to sign Haynesworth to his mega-deal last year. And now, Haynesworth has shown no appreciation for the millions of dollars that were invested in him. Already, this will go down as the biggest free agent bust of all time, and Snyder probably wants to put this in the past as quickly as possible.
His teammates don't want him back
Team leaders like London Fletcher and Phillip Daniels have called Haynesworth selfish, and have publicly called him out for his anti-team behavior. They don't want to work with someone who doesn't want to be a part of the team, and if he came back, the tension would be palpable.
He is lazy
Haynesworth's work ethic after he received his fat contract has been atrocious. It was clearly evident last year, when he was so often winded, that his physical conditioning is completely lacking.
He can't stay on the field long enough to be productive
How many times last year was Haynesworth rolling around on the field after a seemingly minor injury? Too many times. It may have been a ploy to catch a breather on the sideline, or his toughness may leave something to be desired.
The Redskins can't afford to have his negativity affect the team
After the demand to be traded, and after everything that has been said by both sides, the Redskins would be inviting cancer into their locker room if they allowed Haynesworth to play this year. His teammates don't want him around, he seems like he doesn't want to play football, and his negativity could destroy the team unity from the inside out.
The Redskins could use some more draft picks next year
After the deals with the Eagles and Saints for McNabb and Brown, the Redskins will be without a third and fourth round draft pick next year. The Redskins still need a good round of youthful infusion from the next draft, so it would be useful to pick up some extra picks from a Haynesworth trade.