Watergate took years, and this is far more complex of an investigation.  Mueller is actually moving very quickly.  

How would you know it's wasting the nation's time?  Are you on the inside of the investigation?  Nobody knew that there had already been arrests or about Papadopoulus' deal.  He only got a deal because he had something to offer.  I am sure there is WAY more going on than we know, and there is much more to come.