What is utility of materials requirement planning second to manufacturing operations?

It is evolved by MRP-I. A system which incorporates not only material needs, but all manufacturing resources as like various labour types, machine types and another manufacturing resource needed for the type and number of products involved. This could even produce the budgeted cost for every batch or unit of product involved aiding effective production control, planning and cash-flow management. A helpful capability is to answer "what-when" questions.