Is Dark Matter a new bummer like Luminiferous Aether?
Till the first decades of 20th century, all the scientific community believed that the whole space was filled with an invisible substance called Luminiferous Aether (or simply Ether). The concept was first materialized by Newton and it was easily accepted by nearly everyone since then.
The scientists in those times needed a concept like Luminiferous Aether, because they believed that the light was a wave, and surely, the wave should propagate in something (like the water waves need water to propagate).
Now it seems us funny, but in those times, many scientists came up with evidences that the Ether really existed. Many PhD thesis were represented and accepted for researches on Ether. But on the other side, by the beginning of the twentieth century, lots of scientists made experiments that nullify the idea of such an Ether.
At last, by the Einstein's Relativity Theorem and with the concept that light in fact is composed of particles (photons more specifically). As a conclusion, light was not a wave, but compound of particles whose movement act like a wave. This new "paradigm shift" terminated the idea of Ether.
Now, similarly, many scientists believe that such a thing as Dark Matter, does not exist. The anomalies we observe may be (and should be) explained some other way. Maybe Newtonian Laws may vary for very very large masses.