Thank you for such a comprehensive response. I appreciate the code snippet, the link to the add-on, and confirmation that the current version Blender doesn’t allow for the kind of universal overrides I’m looking for.
To expand on my problem, I use keyboard shortcuts and modifier stacks in Quick View to customize objects without requiring I open the Modifiers panel. But as I stated before, it’s irritating to then go into Edit mode and have verts obscured by a subsurf mod, or conflicting wireframes overlapping each other.
In a perfect world, there would be a way to create a listener that would recognize when add_modifier is called, and automatically flip the off switch without requiring I go to the Modifiers panel.
(I’m tempted to drop the suggestion on Right-Click Select, but just between you and me, my previous experience with them has been sort of unpleasantly condescending and passive-aggressive, so I’ve since avoided posting there. Life’s too short.)
I’ve been using an add-on – Tweaked Modifier Tools Addon – that customizes the Modifier panel in a way I really like, and includes a button that allows me to “hide in edit mode” all modifiers on a selected object. And if I Select All and hold Control when I click the button, I can apply it universally.
So I do have a partial solution available to me. It’s just not automatic, which is what I’ve become conditioned to in the age of computers.
But I like your script, so I’ll probably go ahead and make it an add-on for the Properties panel. Even though this is a very esoteric tweak, I may post it here, just so the one other person in the world who has the same issue gets some love.
Once again, thanks for such a thorough and helpful reply. Namaste!