It's not very dangerous, but there has to be a definition of where to stop; to borrow a phrase, you have to draw a line somewhere.
The state of competence among American drivers, at least around here is shockingly bad - most people seem to feel the way you do about slightly crossing the white line about other "minor" infractions like not signaling, not using mirrors, forcing their way into another lane when it's occupied by other traffic, turning into the wrong lane, etc. etc. etc... unfortunately the only law that seems to be enforced is speeding.
nate