I fully understand the inclination to call the move of joining a team that just won 73 games and knocked your former team out of the playoffs "cowardly." Initially, I shared that sentiment. The more I think about it, though, the more I have come to accept this as an honorable decision by Durant.
KD made it clear that he was going to join (or stay with) the team that gave him the best chance of winning. He rightfully believes he'll be able to compete for titles in Golden State. Despite the hyperbolic prevailing opinion currently permeating Celtics Blog, however, I don't think the Warriors are going to be handed nor guaranteed any titles over the next few years. They'll have to earn it. The Cavs will certainly stand in their way, the Spurs will likely continue to battle out west, the Clippers--if healthy--are still going to be a formidable threat, and one or two other teams could emerge out of the mass to move up the ranks and challenge the big boys.
As someone who has been a high level athlete all his life, who is used to competing, I'm sure Kevin Durant is well aware that to win an NBA championship, he is going to have to work like heck and fight like heck to earn one. He knows it won't be handed to him, even if he does play for the team with the best odds on paper. It sounds corny, but championships are indeed not won on paper. They are won on the court.
The rest of the NBA is now surely going to galvanize towards stopping the mighty Warriors. They will have to prove themselves on a nightly basis. The pressure will be on. Durant wanted that challenge. Now he's got it. I sure won't be rooting for Golden State next season, but I can respect Kevin Durant's decision to join them.