There's nothing wrong with "B" and "C" tickets. They made up a lot of the charm of MK back in the 70s/80s. The problem is when the online fan community--with a push from Disney social media--begins to think of a new B or C ticket as something more. That leads to disappointment. Yet to see Sparrow (did if soft open yet?), but I imagine if you've been building it up in your head for months, it fails to live up to hype. If you're a random guest who just stumbles across it one hot August afternoon and kills 15 minutes in there, it's probably a satisfying diversion.
ETA Not to say the park doesn't have substantial problems and need another E ticket or two. Just saying putting a new B in, or a new Disney Junior show, doesn't really affect that equation one way or the other. I think it should be judged on its own terms, not as a potential savior or Potter swatter.