I think that you are missing a key creative tool by not having an easy way to save masks. Without it , it just brings my creativity to a screeching halt when I am trying to do variations of a picture with different adjustments.!!!
Have to agree & seems like it would be a relative easy add.
Are you aware you can copy masks from one adjustment to another, and from one image to another and even use the copied mask to mask the overall effect.
and if you save a project as a project file then masks will be there upon reopening.