Powerful people meet all the time. It may be the mayor and the local fat cats or it may be the governor and more and bigger cats or it may be national or international. None of these meetings would benefit from public announcements, regardless of what is discussed, and yes some crooked deals are sometimes hatched in such meetings but not all of them for sure.
I suspect they (the Bilderberg group) do talk about what is going on in many realms, including politics and the international monetary conditions, and they may even pick each others brains, but I see no sinister plot to control the world because it can't be successfully done.
If they met openly would there be less suspicion? Regardless of how low-key the meetings are the press always knows and announces them. If they were publicly ballyhooed wouldn't the press demand press conferences to explain what went on? If so, that would destroy the value of the meetings. IMHO, the whole effort is to avoid dealing with the idiot media.