Does a tree have to have all of the traits you have mentioned to be considered a Pre-Bonsai? If it has only a couple or a few of these traits is it still a Pre-Bonsai or is it something else?
At what point in a tree's development does a tree become a Pre-Bonsai. Also you must consider this. If a tree is sold by a bonsai nursery and has none of these traits imparted upon it by the hands of the nursery grower other than some sort of selection process and, it just happens to be a nice tree any way, and a large price is charged for the tree is it still Pre-Bonsai?
There is no formula for beig a pre-bonsai. It's subjective.
The point a tree becomes pre-bonsai, is when a bonsaist decides for himself that the material is good enough to work with. This is different for every person. I may be able to see something in a tree, that makes it precious for me. It can be a twist in the lower trunk. A unique feature. Another person may not be able to see that, so for him, it's useless.
An untrained yamadori that I collect is definitely a pre-bonsai for me, since I collected it for specific reasons (bark, trunk, deadwood, whatever). It may not be interesting for others. For me, it is pre-bonsai. For the next guy, it's not.
I don't care whether or not the features that make a material unique for me, were made by man or nature. The tree could grow in a nursery can and develop some nice features by itself, without being bonsai-trained. Or it may have gone through some initial pruning and wiring. It's all the same for me, it's pre-bonsai. It can also have many attractive features, or just a single one, in my eye. It is still pre-bonsai to me.
So, one cannot take out the subjective aspect of calling something a pre-bonsai. Just like calling art something, may be subjective. Sometimes, it is obvious to the whole world that something is pre-bonsai. It has many great features, but it is still raw. So, it's a no-brainer. Just like many works of art look art for everybody. Other times, a tree may have features that are hidden to most of us, but a few with great imagination. To those, it's pre-bonsai just the same, but not to the rest of us. There is no rule to it. It's in the eye of the beholder.