You are probably right. But I only trace buildings that I have to refurbish/convert, and I always double check measurements on site. The only other scenario I can think of for tracing buildings is for archviz, where that accuracy doesn't seem needed to me.
All my other buildings are modelled directly in sketchup.
An advice I'd give you if you want to really use CAD imports is to group it and trace over the group with the rectangle tool. That will assure the orthogonal results which sketchup needs