The lack of vision here is staggering. I thought it might be instructive to look at how have other cities have tackled areas like this. Here is a street view of the area outside John Lewis in three cities roughly the size of Edinburgh.
Cardiff: https://goo.gl/maps/QhgAztCS7vG2
Glasgow: https://goo.gl/maps/Bk9hBakUci22
Liverpool: https://goo.gl/maps/RVSNyBrqe632
Notice any unifying themes? All dead centre of the city, all pedestrianised, no thundering traffic canyon. It's not that it can't be done. Choices have been made in these places, the same as they are being made in Edinburgh.
Surely it is now clear that cities (including Edinburgh) can't ever cope with the level of private vehicular traffic that might wish to travel there. Maximising traffic flow here simply moves the blockages along to Broughton, Leith, The Bridges and elsewhere - to the detriment of people who live, work and shop in those areas.
This is the most easily accessible part of the city - the Waverley, Bus Station, Tram and local buses all serve the area. Yet the city chooses the worst possible option to manage access by private cars - rationing road space by congestion. Community severance, air pollution, noise, injury accidents will all be higher - and for what? So the minority who choose to pass through the area by car (many never stopping) might have a slightly shorter trip.
What is the alternative? Removing general traffic lanes, prioritising public and active travel, improving community life - make driving harder and the alternatives more attractive and people will leave the car at home. Remember - car ownership in the Netherlands and Denmark is actually higher than in Scotland. Are Scots uniquely stupid when it comes to travel choices? I don't think so.