Have not read the whole thread, just responding to OP:
"So, if you actually bushwhack,"
I do. I spend about 20 nights out backpacking a year, and about half of these nights are off-trail/bushwhacking trips. I do a lot of day trips too, especially during berry and mushroom season, and I would say 75% of my day trips are not on any official trail for at least some (if not most) parts of my hike. This is one of the main reasons I opted to have my go-to pack (Zpacks Zero) made in all hybrid Cuben, including the front pocket, and I love it. No holes or major damage after a year of use, and hardly any minor damage either. I put one tiny patch of duct tape recently on a tiny (1cm) scratch in the outer fabric, but didn't go through the inner Cuben.
"where do you do this?"
Sweden and Norway. Sometimes Spain.
In Sweden we have some of the best laws (if you ask me) as far as backpacking and nature go. It's both a trail hiker and bushwhackers paradise IMO. You can read more here: http://naturvardsverket.se/en/Enjoying-nature/The-Right-of-Public-Access/
"Why do you do this?"
Less people, and actually most of the time no people where I go. I enjoy experiencing a more wild nature experience, less or not disturbed by humans. I also enjoy the peace and quiet of hearing only the sounds of the woods--no talking, no cars, nothing civilized. And privacy is nice for a variety of activities ;)
I see more animals, and I very much enjoy observing them. The time I watched a gray fox walk down to an isolated lake I was meditating by and have a drink and then calmly trot away without noticing me will stay with me forever, for example. Or the time I sat on top of a boulder and watched deer feed under it, about 3-4 meters away. I could go on.
For my day trips to harvest berries and mushrooms, the further out there I get, the more bounty I can collect. Two years ago I was able to harvest a total of 16kg of wild mushrooms--it was a particularly good year for mushrooms that year, and I also found a few new spots way out there that are some of my best kept secrets.
Sometimes when I hike on trails there are areas on the map that look interesting that I will want to explore. Here is an example of that:
"How far do you bushwhack at a time?"
Depends. I have done three day trips, they take more planning and attention to detail, especially for obvious safety reasons. But it can be much slower than trail hiking, so usually around 10-15km a day is what I aim for rather than 20-30km when I am on a trail. I am definitely more tired after off-trail/bushwhacking trips at the end of the day, I would note.
On day hikes I can cover more ground because I usually go to areas I know, but it's hard to give estimates of day hikes for me--I just don't pay as much attention.