Ken Kifer patiently describes and distiguishes among the many nuances of touring on his bike pages. http://www.kenkifer.com/bikepages/touring/camping.htm

For him, "Bikepacking" referred to his own version of bicycle touring, where he camped in the woods and prepared his own meals. Off-roading wasn't necessarily a part of it for him, although he did always camp off the road.
As far as I know, Kifer is the one who coined the term "bikepacking." At least, he is the person from whom I lifted the phrase. If Mr. Kifer were still around, I'm sure he would have lots to say in these touring forums.

In reading Kifer's down-to-earth excerpts like "College Camping vs. College Football" and "Our Estrangement from Nature," it's weird how much I can identify with Kifer and his ideas about modern society and how cycling fits into people's lives.