I would think a tool that can quickly do high quality building extraction would end up displacing the efforts to add buildings to OSM.
Such a tool would have a couple of advantages; the capture dates of the imagery used would be well known and the coverage would be consistent. The projects to add buildings are often hasty and involve lots of people of varying levels of experience (and diligence and so on).
Of course, there seems to be a widespread (and incorrect) mindset that working with OSM only is somehow vastly easier than working with OSM plus some external data. It's nice that data added to OSM automatically shows up in lots of places, but it is usually quite straightforward to use other data alongside the OSM data.
Such a tool would have a couple of advantages; the capture dates of the imagery used would be well known and the coverage would be consistent. The projects to add buildings are often hasty and involve lots of people of varying levels of experience (and diligence and so on).
Of course, there seems to be a widespread (and incorrect) mindset that working with OSM only is somehow vastly easier than working with OSM plus some external data. It's nice that data added to OSM automatically shows up in lots of places, but it is usually quite straightforward to use other data alongside the OSM data.