The idea of modifying general relativity is called as MOND and has been thoroughly investigated by physicists. There are still proponents, but I think the models are not matching the observational data. Also, the fact that Galaxies with similar (visible) masses have different levels of rotational momentum seems to hint that dark matter is a thing. I don't understand why people think having something that interacts with fewer forces than normal matter is more complicated than Jerry rigging a change to the elegant general relativity.
Dark matter is easily the most popular theory for this observed phenomena, so clearly most people do NOT think having "something that interacts with fewer forces than normal matter is more complicated than Jerry rigging a change to the elegant general relativity."
I'm not sure if you are saying that I think one is more complicated than the other because I do not. I'm simply wondering about ideas and asking questions. Surely we should still ask questions, right?
