I'm gonna go ahead and say it because no one else has, if something that doesn't need to affect you ruins something you like then you have really ****** mental toughness (or more accurately, get annoyed or worked up too easily). The normal response is not to let a bad film ruin the one before it even if they have continuity in the story. No one should be saying anything along the lines of "Independent Day was good but then ID 2 sucked so now I don't like the original".
Anyways, you have critics telling you that such and such sequel including that one sucked, you then have ratings websites telling you it sucks once it's been out for a week plus, and you live in 2016 where you can easily check this so if it disappointed you and didn't live up to the original then sheesh, what were you expecting.
I don't care if they keep making sequels, I'm sure 90% of them will be crap, just watch the ones that are good or that you have an interest in watching.
I think the flaw in this statement is that it assumes that a person should value wanting immediate enjoyment in isolation over wanting to be accurate/honest and, I would argue, the greater gains that result from that. It's similar to the lowering expectations argument, which seems similarly flawed to me.
An experience that does not have bad followups is noticeably more enjoyable and satisfying to me than an experience that does. While perhaps the latter can't directly take away from the positives that undeniably already exist, it can be considered a negative that is introduced to the equation. Therefore, it's sensible to suggest that a movie can be somewhat "ruined" (made to not be as good as it otherwise would have been, or prevented from being perfect) if that negative exists. Given that this is how I see it, asking for it not to be factored in simply because the negative can be ignored, avoided, or predicted is basically pleading that self-delusion and ignorance is the best policy when it results in something positive. I think this is a terrible reason to do something.
Personally, I
want to acknowledge and consider the negative effect of bad followups, because I value significantly more, the positive effect of something that manages to avoid it. If I ignore the former, it would only be logical to ignore the latter, which, to me, would be more unfortunate.
Someone can feel differently and it might not be a factor to them (and as a result, they wouldn't appreciate the drawback or benefit of its consideration), but it can be a reasonable factor to others (as it is for me), and it has nothing to do with mental weakness, emotion, or stubbornness, but instead has everything to logic, principle, and big-picture satisfaction.
For example, I think the first six years of The Simpsons is a masterpiece, and it's one of my favorite shows of all time, but the twenty additional years of awfulness is still a negative that I can't deny takes away from it. Does it ruin the show to a point where I hate it? No, but it does ruin the fact that it would have otherwise been perfect and untouchable (which is not nothing). If I tricked myself into thinking that it doesn't take away from it, I would have to lose some appreciation that I have for shows that don't have this flaw. In the equation that you're concerned with, of having the best time possible-- There is a trade-off that is inescapable, and I'd rather give credit (and consequently, criticism) where it's actually deserved.