Nobody ever said that understanding what the brain does is going to be simple or easy to explain.
I find it hard to imagine that modeling the entire visual hierarchy and all the sub-mechanisms at each level could be much simpler. This is an enormously complicated task and this paper combines years of prior papers into a masterwork showing how all the parts can work together as a system.
The emergent property of counterflowing streams of information interacting to guide memory formation can only emerge at this level of implementation. This is a highly desirable goal.
I am impressed by how much of the visual system they have captured and how well it does work. I am trying to see how to incorporate many of the features of this system in my own work. I think that combining that insight with the HTM SDRs and predictive behavior should work even better. It would be great to see the training time drop from hundreds of thousands of trials to a few dozen.