rigging needs to be for something specific. It has this name because it was meant to be used on ship rigging used by ship girls - think nets, anchors, bridges, railings, radio antennas, control towers, etc, but used as components of a costume. The kind of stuff that if you just tagged it as it is, it would poison the main object tags, and that you can't search for all at once without having to include 20 different _ornament tags.
This tag was needed the moment we decided not to tag kancolle with personification, otherwise it would've been redundant with it. This is not a problem for other vehicle personification copyrights, because, well, none are anywhere near as big as shipgirl copyrights.
In theory it would make sense to use this tag on things like tank girls or airplane girls, but it would significantly increase the scope of the tag, and if we're dumping it on all kinds of weird metal components then it becomes complete padding.