Our view of hierarchy has changed, somewhat. We now realize that individual regions are far more powerful than we previously thought. It doesn’t make sense to focus on hierarchy until we completely understand what regions do. For example, there are several different sources of both feedforward and feedback signals in the hierarchy. These originate and terminate in different cellular layers. We need to understand what type of information these layers represent to understand what we gain from a hierarchy.
We are actually getting close to understanding all/most of this, in fact knowing that some layers project up or down the hierarchy helps us determine what those signals are, but we are not ready to focus on hierarchy yet.