Since Blender 2.8, the Remesh modifier defaults to the new Voxel mode. This is a great new feature, but its performance is directly tied to model size and complexity. I routinely work with large (1000+ unit scale, 10,000+ faces) models which consistently cause the program to crash when I try to add a Remesh modifier. To work around this, I have to add the modifier to a default cube mesh, change it to another mode (e.g. Smooth), and then copy the modifier to the intended model.
Most of the time, though, I forget to do this workaround and accidentally crash the program. It is a similar experience to accidentally adding a Bevel modifier to a complex model.
Until we’re able to escape out of hanging processes (some sweet day) it would be amazing if we could change the default back to Smooth.