The reason it's never been brought up in the past two years is because you've framed a scenario no reasonable person would argue against:
I've read a little about the book/movie/…, checked its Wikipedia article, googled a bit, and didn't find the answer to my question.
The context, however, of bringing this up now is your answer on "Is general reference used inconsistently?", where you claimed (emphasis mine):
Note that asking questions about a movie does not require having seen the movie, let alone be intimately familiar with every character.
as a defense to not closing a question as "General Reference" even though it was demonstrably shown to be something that anyone checking the Wikipedia article for or googled a bit would've gotten an answer to.
If a question is easily answered by a reference, regardless of whether or not the person asking did, in fact, do that research, it's closable as "General Reference". If someone legitimately did basic research before asking a question of this ilk, the whole problem doesn't come up.
But what we're really talking about asking a question blindly: that is, I know nothing about a movie, didn't do any preliminary research, but I want to ask a question about it.
Like I said above, the motivation or background for asking the question has very little, if anything, to do with closing a question as "General Reference". While unlikely, one could ostensibly stumble blindly into asking a really difficult question that's not easily answerable by a general reference.
But that doesn't mean SE doesn't expect or require users to do basic background research before asking questions, because it does. For many forms of media, that which you enumerated—checking the Wikipedia article or googling around a bit—is a good place to start. For movies, however, it's reasonable to expect people to have watched them for two reasons:
Having seen the movie helps demonstrate this is an actual problem you face.
Movies are generally no more than 3 hours long, with most these days in the 90-120 minute range. If it's something you're really interested in, taking 2 hours to watch the dang movie is the least you could do before asking.
Which leads to what it means that something is "required" or "expected" if it's not to close a question. There are at least two things:
But, to reiterate, the Dark Knight Rises judge question is not "General Reference" and did not need to be closed because the person asking did not see the movie.
Rather, it was closed and should remain closed because it was easily answered if someone did take the time to do some basic research before asking it.
Or to put it another way, you don't have to do any preliminary research before asking a question, but don't be surprised if your question gets closed for being "General Reference" or you get a number of down-votes for asking it.