It seems to me the confusion is over what OpenStreetMap wants to control and what copyright allows them to control.
The 'shortcomings' of CC-BY-SA noted in your first link seem to boil down to use cases involving chunks of data that simply do not qualify for copyright. Thus, by definition, no copyright license could behave any differently than any other in determining what can and can't be done with those chunks of data.
A Terms of Use agreement (and enforcement) could do more, but the particular copyright license is simply moot.
The 'shortcomings' of CC-BY-SA noted in your first link seem to boil down to use cases involving chunks of data that simply do not qualify for copyright. Thus, by definition, no copyright license could behave any differently than any other in determining what can and can't be done with those chunks of data.
A Terms of Use agreement (and enforcement) could do more, but the particular copyright license is simply moot.