Both at Crooked Timber, and in my own beloved comment threads, the suggestion has been made that the minimum wage is really swell because it gets rid of low-productivity jobs that only pay the minimum wage.
This sounds lovely--if you are the kind of person who has the skills to get one of the higher productivity jobs. Not so great if you're a high-school dropout with no appreciable credentials. In effect what you're talking about is a massive transfer from the weakest members of society.
Let's say raising the minimum wage makes them unemployable, while creating new, higher skilled jobs making and maintaining the equipment that replaces them. Good for skilled workers. Possibly good for society in some sense, though raising unemployment is rarely a net boon. Definitely awful for the lowest skilled workers, who now can't get a legal job.
Helping the moderately paid worker by forcing the least skilled out of the legal job market is a very, very bad policy. Whether or not you think that the government ought to be in the business of transferring wealth from one segment of society to another, I hope we can all agree that at least the transfers oughtn't to go upwards.