Eloquently and cogently put. Only thing I would point out, at the risk of beating a dead (or dying) horse, is that SOME flaws can objectively be identified as flaws -- for example, the many grammatical errors in the lyrics of MY FAIR LADY, or the fact that Judy Garland's hair style keeps changing from scene to scene during a sequence in A STAR IS BORN that's supposed to take place during one long night. So in cases like that, I think we would have to say that some people simply don't care about those flaws even though they are clearly flaws, either because they don't think they're important, or deep down they really DO think they're important but they just don't want to focus on them or discuss them because they love the movie or the show so much overall :-)
That said, I think we can all agree that most perceived flaws do not fall into this category and are completely subjective -- for example, the problems some of us perceive in the book of FOLLIES. So your point is very well taken.