The major problem is interpreting the findings in already published neuroscience studies so that a model could be extracted. HTM research is not capped by biological information, never really was. Does more information help? Definitely. Though it is more about filtering and converting that biological information into functionality because there is A LOT OF information. Typical neuroscience studies do not directly ask questions that HTM seeks to know, at least in the past this was the case. So we have to generate our own answers based on those studies. That is the hard part and the answers may even be hidden in works that were conducted a decade ago. So @cogmission has a valid concern about time and staying focused on biological intelligence systems.
On the contrary, neuroscience studies may need to be guided by the needs of general AI systems. Knowing what you are looking for is a huge advantage for any research because we cannot even understand how a microprocessor works by conventional neuroscience methodology. There is only so much you can do without trying to model and without understanding the functional challenges.