the main justification for complete streets is that it improves the quality of life. It certainly isn't coming from cyclists, although there is some overlap. We have a street near us that would be much better as a pedestrian plaza, but instead it is dominated by people driving around looking for a parking space. There are something like 15 parking spaces on the street, but you have people driving around the block, making u-turns, and generally creating hazards for pedestrians.
We now have a situation where every road has to be able to handle the cars at full speed +10. This needs to change.