If the nervous system is wired up such that there are no well defined layers, how does this compare to a neatly stacked artificial net? If between my sensory and motor side I had a neatly designed SNN with well defined layers, how would I see the world? I get that there are some evolutionary advantages to a system where information can sometimes take a shortcut from sensory cell to motor cell (reflex action) bypassing brain processing but for arguments sake let's talk only about intelligence.
The human nervous system is an extremely dynamic entity, having been formed by the processes of embryogenesis, mediated by various markers guiding neurons to grow to specific areas, and all of it laid down by millions of years of evolution. There are many different varieties of neurons in the human brain, indeed more so than pretty much any other animal on this planet.
It is hard to see that a spiking neural network (SNN) would be able to get all these details correct when we don't yet fully understand the biological analog.
I think for this to be successful, we need to understand much more about not only the variety of neurons in the brain, but details of the the embryogenic dynamics as well. And not just the neurons, but the glial cells as well.
Having said that, there is something to be said for using evolutionary approaches to resolve "a solution" that may work anyway. Taking this approach will require many more resources, but is perhaps doable.
All in all, I would not expect a naive attempt of the neuromorphic SNN to succeed. There is a lot of complexity involved in what the brain does, and it involves the glial cells to a large degree. Do we understand enough about the role of glial cells in the brain? We cannot ignore them. Are they only performing "housekeeping" operations, like, for example, the uptake of "spent" neurotransmitters? Or are they doing more, taking part in the computational and / or memory aspects of the brain?
There is much research in this and other pertinent areas that one should look into. And expect a lot of surprises.