Why not sort out the roads in the first place by educating drivers to use the spare lane (ie. lane 1) on the motorway for starters?
a scary place for middle lane man, and an obsticle for 3 series man
seriosly though, what if a car were to konk out in a normal lane?
youd usually coast into the hard shoulder with your hazards on and stop safly as nopbody were coming, but with it being used as an extra lane, you might not make it and stop in lane 1, causing a jam, or get on the hard shoulder and be wiped out.
but there again, lots of people still drive down the hard shoulder in heavy traffic, even though they arnt supposed to. it just take on person to do it, then somone else will, then someone else, and that pattern continues on and on.