MOND remains popular because it's made so many successful a priori predictions that DM failed to do. At the risk of being too reductive: DM is popular among maths-oriented astrophysicists because as physicists they like particles and deep theories, and MOND by contrast, doesn't have a full theory justifying the adjustments to gravity and they don't like that; MOND tends to be more popular among astronomers than astrophysicists because they like effective theories that make successful predictions using few parameters, and MOND is somehow better at that (as with this paper).
It's easy to be a MOND enthusiast without a physics PhD, it's a lot harder to be an axion or WIMP enthusiast.
"Just tweak the laws of physics, bozos!" is a really easy idea for laymen to latch on to, which is why you see so much interest in it among science enthusiasts.
"The experts are wrong because they are overcomplicating things" is also just a rhetorical trick that has pretty much always worked on some segment of the population.
It's because people don't like the idea of matter that you can't interact with especially if it makes up a double digit percentage of all mass in the universe.