This is clearly not a pervasive issue. I for one have no such problem and if this was affecting the majority of people there would be a major outcry I would think.
So with that in mind, there is clearly some difference between those cars that have the problem and those that don't. Yeah I know I am stating the obvious but hang in there.......
I cannot believe therefore that the root cause would not by now be understood by BMW. I expect that they would have a detailed database of every component on every car built and could readily identifty commonalities between those cars reported as affected. On that note......is everyone with the issue going back to their dealer to complain???
So if I believe that they know the cause, then I would extrapolate that the solution is not straightforward or it would be implemented. A software fix it probably is not. Is it more likely that there was a component from a different supplier or a certain batch that causes this issue? As it's not a life threatening safety matter I doubt they are obligated to do it. As it's a relatively low subset of people experiencing it (as opposed to every single magazine review shouting about it) perhaps the strategy is to sit tight and ignore the small percentage of affected owners.
Or maybe I am a conspiracy theorist who is talking out of his arse.