There are a bunch of physicists who work on modified gravity theories (that include MOND). The reason why most of us focus on dark matter is because in terms of significance this idea is stronger. This however does not mean that modified gravity theories are excluded and that no one cares about them. They are tested too.
At the end of the day, what is important is that all paths are explored, which is the case.
Thanks for the answers! Dark matter seems like a very exciting field to be working in at the moment.
I fully agree. :)
This is why I have dedicated a significant fraction of my research time to dark matter during the last 5-6 years.