I think every physicist on the planet would love a nice elegant model of gravity that explains away “dark matter” observations. The next layer after Newton and Einstein. Clean and simple.

… but that’s just proven to be very very difficult. Evidence for dark matter comes from a wide range of observations, and while it’s pretty easy to come up with relativity replacements that could explain things like rotation curves nicely… other observations, from lensing and colliding galaxies like the bullet cluster are, just, well, messy.