I entirely agree that importing buildings in mass is not something I'd want an inexperienced editor attempting on their own.  It does appear that if you manually draw a building from imagery, they would leave that alone and the quality would likely be better than what they intend to import.

That's up to you if its worth the effort.  However, if you expect and automated import is going to take care of this, it may also be wasted effort to tag the sites of missing buildings.

statcan.ca looks like a amazing resource, although I've yet found where building footprints would be.  I suspect it's possible that you could download these and select buildings individually for import.  I've done similar work with files from the National Hydrology Database in the US.  I wouldn't consider myself compitant to write an algorithm and let loose on the map, but I can load the data into my editor (JOSM) and import lakes and rivers individually.

