What Marx gets wrong about wages

Why does Marx's calculation of the "wage minimum" include the cost of labor reproduction?

Marx, in Wage Labour and Capital:

What, then, is the cost of production of labour-power?

It is the cost required for the maintenance of the labourer as a labourer, and for his education and training as a labourer…

Here, however, there enters another consideration. The manufacturer…takes into account the wear and tear of the instruments of labour. If a machine costs him, for example, 1,000 shillings, and this machine is used up in 10 years, he adds 100 shillings annually to the price of the commodities…In the same manner, the cost of production of simple labour-power must include the cost of propagation, by means of which the race of workers is enabled to multiply itself…

Thus, the cost of production of simple labour-power amounts to the cost of the existence and propagation of the worker.