I don't want to nitpick but I feel compelled to tell you that this has nothing to do with anything else you said. Appraisal of art on purely artistic grounds have nothing to do with morality. If I see a painting and say "this is ugly" it's not a moral judgement, it's an artistic judgement. I absolutely agree with you that moral judgement is a matter of opinion and not fact, and I also agree with you that artistic judgement is opinion and not fact. But still artistic judgements and moral judgements are two different things. Your comment about morality in a text about the subjectivity regarding the quality of The Simpsons comes right out of the blue.
Well, appraisal of art and fiction may not be tied to morality in your book, but it does in mine because both appraisal of art and morality deal with what we believe to be good or bad/right or wrong. "Good" and "bad" are relative terms because they are different in meaning from one another. They are also both subjective (therefore opinion-based) because they are tied to our feelings and our thoughts. So there is (sort of) an overlap between art and morality.
Sorry, I don't mean to be a know-it-all but I cant help myself.
Anyway, in regards to the actual topic, I understand your point regarding how The Simpsons is one of those things where the idea that, at least it's golden age, is of great quality has almost become accepted as objectively true. Honestly, I feel that in this regard The Simpsons is to the medium of television what Don Quixote is to literature or what the Sistine chapel's ceiling paintings is to visual art. It's one of the things where it might be okay to say "I personally don't like it" but it's not okay to say "It's bad". And regardless of what one personally think is reasonable when it comes to the question of whether art can be objectivey good or bad, the sheer fact that the golden age of The Simpsons appears to be one of the few television shows that have found itself, in popular opinion, in the "objectively good" camp is interesting. How many other television shows are comparable to The Simpsons in that specific regard? As fas as television shows that are universally known (as opposed to ones that may have recieved nearly unanimous praise but are too obscure to be placed in the "everybody knows it's great" category) I can think of one; Seinfeld. Saying "Seinfeld is a bad show, and by that I don't mean that I personally don't like it but rather that it's simply bad" will make anyone lose all credibility as far as their understanding of scripted television shows go. Classic Simpsons is in the same boat.
I strongly disagree with the idea that "I personally don't like it" and "It's bad" are different in meaning. No, they aren't! If I don't like something, then it IS bad, to me. At least that's how I would rate something. If I give a work of art or fiction a low star rating, it's because I detest it; it has to do with my thoughts AND my emotions on it. Just because a movie may be (sometimes surprisingly) highly rated on IMDB, doesn't mean it's "objectively good" or that I must accept it as such. I could name examples of fictional works, such as movies, that I call "bad" but I won't because so many people won't understand or (worse yet) they would "debunk" my contentions and call me a "baby". But here's the thing though,
The Simpsons is not objective good.
The Simpsons is subjectively good. The Simpsons is objectively an American animated television series that started in 1989 and created by Matt Groening.
The former statement is a matter of opinion and the latter is a matter of fact.
And it's funny how you mentioned Seinfeld. No pun intended. Because to me, it's a terrible sitcom because I don't like it, but SO many people do like it and think it's a great sitcom. Good for them. That's the same way how I feel about M*A*S*H; it's unfunny trash (which rhymes with mash) to me, but to "everyone else" it's a witty masterpiece.
And anyone reading my post, PLEASE don't get all butthurt because I said M*A*S*H is unfunny trash because it is to me. I fucking hate that show! It's shit! The movie as well. So, please don't judge me for having the contrarian and frankly unpopular opinion.
Personally, The Simpsons is FAR superior to Seinfeld and M*A*S*H because I enjoy The Simpsons WAY more! The Simpsons is a great show when compared to M*A*S*H and Seinfeld. It's all relative (to my opinion)!
I am one of those people that can be annoyed by the universal insistance that something is good (or bad) but I have to be honest and say that I can't bring myself to be upset with the fact that classic Simpsons of all things have acchieved the "objectively good" stamp due to the simple fact that I personally truly think it's the best television show of all time.
Well, if you ask me, it's very contradictory of someone to say that "I don't like
X" and say "
X is great." What the fuck?! I can't and won't call something or someone I don't like great. Never! I refuse! I would only call something or someone great because I like them. I proudly rate things by a binary system. My enjoyment of something or someone cannot be separated from its greatness.
But in my opinion, The Simpsons is good. 
