Streetcars in Toronto are like this too. Cars are required to stop when the streetcar doors open; the needs of one driver do not outweigh the needs of the many passengers getting on and off. That said, yes, you should look before you step down onto the street.
The cost? The cost in increased congestion when cycling is made less safe? The cost in pollution? In human lives from increased road deaths? How about those costs, Doug? The costs that matter most?