[qrendel]

These types of questions seem to come up a lot, and while I'm not an expert, here are some typical responses, from one of the last dark matter threads (in particular, the two top replies): https://news.ycombinator.com/item?id=10550732

I assume the tendency for the general public to give higher consideration to "other explanations," relative to professional physicists who seem to lean heavily towards the "matter" hypothesis, is lack of expertise in the current state of research. If you don't have a lot of good evidence one way or the other, all options seem about equally likely, so why take WIMPs more seriously than MOND or other hypotheses? Not that considering those alternatives is silly, but I think this might explain why this question keeps coming up even though the physics community seems pretty focused on the dark-matter-as-matter hypothesis.

Though whatever the answer should turn out to be, it will certainly be an interesting development.