I'll go along with MONEY PIT's level headed answer. The mfg has to cover his butt in case a car owner spends time driving through 10,000 ft mountain passes and such. For the average driver rotors that have reached minimum limit are not a risk in my opinion. Also in my 30 years as an MB mechanic, I've never seen a piston pop out of a caliper when pads and rotor have reached minimum thickness. Maybe they should, because that would pucker the butts of people who buy new CDs and neglect their brakes
