According to wikipedia, superheroes are classified under "Superhero fiction" in the science fiction genre, and is almost a totally different genre in itself:
Superhero fiction - Wikipedia, the free encyclopedia
I'll paste this from the definition of science fiction as Wikipedia defines it:
According to science fiction writer Robert A. Heinlein, "a handy short definition of almost all science fiction might read: realistic speculation about possible future events, based solidly on adequate knowledge of the real world, past and present, and on a thorough understanding of the nature and significance of the scientific method." Rod Serling's definition is "fantasy is the impossible made probable. Science Fiction is the improbable made possible.".
A movie based on scientific facts and strongly follows laws and principles of nature doesn't necessarily have to be boring. Thus it also follows that a sci-fi movie doesn't have to be inaccurate for it to be entertaining. As an example, when talking about "secret agents", McGyver is a more realistic representation of such an individual, than say James Bond (i.e. he makes use of what he has around him, rather than depend on some do-it-all gadget that makes life easy for him), yet it doesn't make him less interesting than Bond.
I believe that the plot of most of the sci-fi movies out there (or the ones that claim to be sci-fi) are not inaccurate because "the audience wants it to be inaccurate". I think the reason why some of them tends to be inaccurate at times, is simply a product of poor research on the subject matter, and perhaps, may I dare to say, a certain amount of "laziness" on the part of the writers/producers, in the hopes that "Oh, the common Joe won't notice that" sort of mentality, which to me, is pretty much insulting the capacity of human intelligence and wisdom.
It also doesn't follow that "money comes first" in the movie industry. There are a lot of "over the top" science fiction films out there that promised to be "entertaining", but the general audience is smart enough to know when it goes overboard, and thus it doesn't fare well in the box office.
-RODION