So is removing on-street parking always a bad idea? Of course not!
It may often be a great idea to remove some parking for the sake of other priorities besides parking and traffic flow. These include bus lanes, bicycle facilities, drop-off/pick-up points, loading/unloading, taxi stops, pocket parks, walking space, etc. Any or all of these might be a good idea depending on the situation. They tend to build the accessibility and attractiveness of the area rather than focusing just on moving vehicles.
Bottom line: Please be cautious when you hear someone calling for on-street parking to be completely removed, especially if it is for the sake of traffic flow.