Unparenting a mesh from an armature object also deletes it’s armature modifier if present.
I can understand how this might make sense in a really simple case. In other words, a mesh object + armature object.
However a rig is usually much more complex than that, with possible multiple armature modifiers and other deformers (mesh deform, hooks, relations to other objects, etc.)
The fact that unparenting decides to remove a modifier in such a hidden and forced way is completely unexpected. Even more surprising when removing the parent by Shift + Dragging over the outliner, only to discover (later) that the armature modifier was long gone!
At least when parenting the option to add a modifier is explicit and… optional.
In the case of unparenting it just messes with your modifier stack without notice.
Yeah, this is one of those cases where Blender tries to be smart, which means that it’s treating users as if they’re stupid. Sometimes Blender’s right, sometime it’s not.
This is also the case with a curve modifier and IIRC with path animation.
The reason is that Blender has options for easy parenting to automatically create some other stuff when it parents an object-- for example, parent with armature deform. If unparenting is going to undo everything that parenting does, then it needs to undo those automatically created modifiers etc as well.
But of course it doesn’t have any record of how those modifiers were created.
Should be said that Blender’s behavior in this regard is really weird. Sometimes it removes those modifiers. Sometimes it doesn’t. If you parent armature deform, copy the modifier, unparent, it deletes both modifiers. Trying to work around this, in order to get something with automatic weights but a non-armature parent, can be really irritating.
At the very least, there ought to be “smart” and “dumb” unparenting options from the menu. I mean, there’s already a menu, the UI hit has already happened.
This is why, every time I need to set up a skeletal animation, I must watch a Youtube tutorial and follow the instructions to the letter, because one wrong step messes everything up.
The whole armature user interaction experience in Blender is extremely convoluted and fragile.
