The idea that the minimum wage is just a stepping stone to better employment and was never meant for the long-term is simply historically incorrect.
Franklin Roosevelt was the father of the minimum wage. In his 1937 message to Congress establishing both the minimum wage and a limit on weekly hours worked, FDR made it clear that the purpose of the law was to aid workers in their permanent occupations.
Starting his speech by noting that "One-third of our population, the overwhelming majority of which is in agriculture or industry, is ill-nourished, ill-clad and ill-housed," Roosevelt went on to say:
"Today, you and I are pledged to take further steps to reduce the lag in the purchasing power of industrial workers and to strengthen and stabilize the markets for the farmers' products... Our Nation so richly endowed with natural resources and with a capable and industrious population should be able to devise ways and means of insuring to all our able-bodied working men and women a fair day's pay for a fair day's work."
Clearly FDR, the prime force behind the minimum wage, did not consider it to be a temporary expedient useful only as a spur to greater effort by people too lazy to educate themselves and get better jobs. It was intended from the beginning, and ever since, to be a means of raising the purchasing power of workers who were not receiving what FDR called a "living wage."
The idea that a minimum wage would wreck the economy was strenuously argued by the law's opponents from the very beginning. But their predictions of doom never came true. With the minimum wage in place, the purchasing power of workers increased, and, as FDR intended and predicted, unleashed a far greater level of economic activity than the economy could have otherwise experienced.
It can hardly be argued that the millions of workers today who receive the minimum wage have a "living wage." FDR's purpose for the minimum wage is as valid today as in 1938 when the law went into effect.
History is clearly on the side of raising the minimum to something workers can live on.