Let's assume the worst because maybe it will seem better if the worst doesn't happen.
I mean, I see where you're coming from, but to me it just seems like pessimism.
As silly as this sounds, you're looking at this pessimistically. I'm thinking logically here:
If I expect Microsoft to totally screw up Minecraft, and they do, I am prepared to either settle/adjust to what they create and make the most of it, or move on.
If I expect Microsoft to totally screw up Minecraft, and they don't, I'm pleasantly surprised! Faith restored in Microsoft, let's play.
If I expect Microsoft to totally bring Minecraft to the next level and succeed, and they do, cool. I saw it coming, I guess let's play. Whatever.
If I expect Microsoft to succeed and they don't, forget! How dare they screw this up! Aw man.
It's just a matter of putting myself in a frame of mind that is prepared to deal with Microsoft screwing up a game that means a lot to me. That's all, it's not a pessimistic or optimistic approach.