We have an official course-request list that you can view and possibly submit your request for that. That way we'll make sure it's noted and viewed by those that help decided content that we make. On this one, please upvote this one to add it the list.
When there is a high demand, we try and see if it's in our wheelhouse to do immediately. If not, we search for an SME with availability that we can bring into to do that show.
The hard part is the availability. Many of these highly requested course that is not in the ITProTV wheelhouse are in such demand that SME are hard to find that are available. Put differently, they are busy folks.
The other reason that this may be more difficult in our case is that we cannot use existing courseware for another provider. So that means that our content is authored or put together only for that show. Sometimes, we can if approved by the courseware publisher but this not often from every trainer out there.
Hope this gives a little insight into what has to happen to get a requested course produced.