The idea of release groups is that the releases in there should be mostly equivalent. So, someone who’s not a hardcore collector will generally only need one of the releases in a release group.
For example: I would not consider these two equivalent (neither does Wikipedia FWIW) and I think the current two RGs option is better for them:
That said, your specific example is a bit trickier than strictly “album vs remix album”, so I’m not sure what’s the ideal option there.