Einstein said I have deep faith that the principle of the universe will be beautiful and simple.
This theory strikes me as beautiful and simple and therefore I am drawn to it. The dark matter theory, OTOH, feels "kluged" - like plugging in a variable just so the equation will work. Moreover, we have much to learn about matter - even the existence of the Higgs boson is yet to be confirmed. The Higgs boson is the presumptive explanation for most matter.