>>> How could anyone put a definitive number on that?

If existing metrics are not sufficient, then we need to innovate :) and define new set of metrics to get complete picture.

Actually it is not difficult. Let us register all existing people jobs and one year later register again and you can get the list of jobs that got changed and if you can survey the reasons for change, then you can measure negative/positive impact. There may be refinements to this idea and there can be new ones too.

>>> should we not pursue innovation that leads to increased productivity in existing sectors? Definitely, you need to pursue innovation but what I call "responsible innovation" which is inclusive of society and environmental concerns rather than mere profits.