I think what Roy said about the definition of "competitive" is the basic divide here.
I understand that argument. Winning games in Golden State will be much "easier" for Durant than it was in OKC. In that sense, he took the "easy" route.
On the other hand, we have arguably never seen a team like this new Warriors team ever before.
It is in play that they become the most dominant team ever, possibly for 2-3 seasons or more. They probably already have the greatest collection of talent that we've seen on one team in the modern NBA outside out the All-Star game or the Olympics.
That is something Durant could never have achieved if he had stayed in OKC. The best he could hope for is that his team stayed healthy, had great chemistry, and got hot at the right time in the right year and won a title, similar to what Dirk did with Dallas in 2011, or what the Celts did in 2008.
This way, yes, the challenge that Durant faces individually is less than what he faced in OKC. But he chose to accept the ridicule and scathing criticism he knew he'd get for making this decision, because it would give him a much better chance at being one of the few superstar players who wins multiple rings. On top of that, he might get to be a major part of a team the likes of which the modern NBA has never seen.
What is ignoble, or cowardly, about that? Durant must know that he will now be judged on a much harsher rubric than if he had stayed in OKC. A single title will not be enough. Five more All-Star appearances won't mean a thing. A Finals MVP award might not win over some of his critics in this thread. He will need to help the Warriors win 70+ games multiple times on the way to 3, 4, 5, or more titles. That's the only way he will grab the glory now.
And hey, he might just do it.
I understand disappointment that Durant didn't choose to come to the Celtics, or stay to fight the good fight and maybe go down with the ship in OKC. But I think people ought to at least recognize that it is possible to view his decision a different way -- to consider that maybe Durant just wanted a new experience, a new challenge, and an opportunity to be a part of something that has never been done in the NBA.