I feel the problem is that we're deeply over-trained to read cues for what a car will do, and less so for bikes. To whit, if a bike _could_ dart in front of me, I assume it will. Much like a squirrel, deer, or inner city car in a traffic jam.

Edit: actually, I would probably hit the squirrel. Swerving/sudden speed changes are often far more dangerous. Hopefully the point holds: if you always feel the need to fail safe, then expect congestion and traffic problems.