I know that the approach on Junipers has changed since I started doing bonsai almost 60 years ago but seriously, I don't know why the top of the tree was not opened up a bit to encourage the tree to start growing in a direction favorable to bonsai not a front yard bush. It has always been my approach to open a tree up and let the light in to encourage the growth it will need to progress. I don't mean an insult to Peter, but come on, I would like to hear an explanation to the approach on a tree that has obviously had three years of decent growth where an aggressive approach to the top would not have met with disaster in my opinion. I don't know why bottom growth was not removed, I don't understand why weak growth was not removed, and I don't understand why some styling was not attempted. However; some of the new directions people are taking on Junipers I find questionable, and self defeating, I cannot understand why they are being done.
You are correct that we could have reduced the roots as much as we had, and reduced the foliage of some weak and downward growth, and MAYBE the tree would survive.
We decided that after removing a substantial amount of roots, the tree would recover faster if we leave as much foliage to photosynthesize this spring and summer. Once the tree recovers from the repot we can then move forward to the styling process.
A lot of the foliage on the tree in the future will be it's new branches and help develop the design. The tree elongated the first year and is starting to mound and back bud along the old branches and surprisingly on the trunk. All this growth will give the tree a much better design in the future.
Again yes, someone could have decided to remove weak and downward foliage, we decided this foliage would be more productive in helping grow back roots.
It's not a black & white situation, but more a situational decision that we felt was best for the tree.
Hope this helped.
Also, you are not the first to make this suggestion.