Can be done right
The google effort doesn't work very well yet - select 'by foot' here and it won't let you use any bridges - it insists you go miles out of your way to take the foot ferry across the harbour.
www.cyclevancouver.ubc.ca uses google data but also knows about roads with cycle lanes, cycle friendly 'major road avoiding' routes and best of all - it can calculate routes based on a maximum hill gradient.