Well, I personally liked the writing how it was; it was jarring and WTF-ish, but I think that was exactly the point. We're effectively approaching the whole situation as Dean is; with confusion and struggling to keep up. I think the writers purposefully had Sam come off as cagey and indifferent because that's supposed to be aspects of his changed personality. Am I wrong? Possibly. I guess time will tell. You're totally welcome to have your own opinion, but I personally thought Jared pulled off the writing perfectly, and I'm sure that before long we'll begin to see more of his repression rather than just his indifference.