What hard steps exist between mapping the physical structure of the brain and simulating a running one via software?
The connectome for the C. elegans nematode was mapped in the 1980s and the OpenWorm project has successfully simulated all non-neuronal cells. But they are very far from simulating the brain abd it will take decades of experimental work to understand C. elegans's brain - it's very difficult to observe a living brain in the required molecular detail.
There's plenty of value to knowing where the datacentres are and which regions are active under which circumstances, but none of that is telling you what the internet is thinking...
But the challenges are substantial, and these imaging techniques (mostly optical, not MRI/etc) depend on the simplicity of C. elegans: its brain is essentially a thin disk, with only 300 neurons in its entire nervous system, and it is surrounded by a transparent membrane. I am not sure how these techniques could possibly extend to something with a thick exoskeleton like Drosophila. And there are great difficulties keeping track of just the 300 neurons in a moving nematode with its own unique brain; it seems completely intractable with current tools to extend the complexity 50x, especially since fruit flies move far more rapidly and have far more individual variation.