I think physicists know its an hypothesis, the problem is when its presented to the general public as an universal indisputable truth of science.
You know, those documentaries with the narrator assuming you're a two years old, spoiling the conclusion at the beginning and repeating it as a teaser every 5 minutes? Or all of those "I Love Science" pages. People should stop trying to make science a reality show.
Perhaps we should call it "dark matter hypothesis", but that also gets awkward after a while.