I think cyclists should always ride on the path because it is safer for the car driver and the cyclists. Plus, it doesn't annoy every car driver because they slow down traffic. I've got nothing against cyclists riding their bikes, but what's the point of investing millions in bike lanes when cyclists don't use them and instead, still ride on the road?
However, the only time they use the path is when it is convenient for them - for example when the traffic is at a stand still then they use the path.